WO1993021553A1 - Laser system with mirrors moved by micro-engineering techniques - Google Patents

Laser system with mirrors moved by micro-engineering techniques Download PDF

Info

Publication number
WO1993021553A1
WO1993021553A1 PCT/EP1993/000829 EP9300829W WO9321553A1 WO 1993021553 A1 WO1993021553 A1 WO 1993021553A1 EP 9300829 W EP9300829 W EP 9300829W WO 9321553 A1 WO9321553 A1 WO 9321553A1
Authority
WO
WIPO (PCT)
Prior art keywords
mirror
laser
laser system
mirrors
substrate
Prior art date
Application number
PCT/EP1993/000829
Other languages
German (de)
French (fr)
Inventor
Stefan Heinemann
Axel Mehnert
Walter Kroy
Peter Peuser
Nikolaus Schmitt
Helmut Seidel
Original Assignee
Deutsche Aerospace Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE4211898A external-priority patent/DE4211898A1/en
Priority claimed from DE4215797A external-priority patent/DE4215797A1/en
Application filed by Deutsche Aerospace Ag filed Critical Deutsche Aerospace Ag
Priority to EP93911443A priority Critical patent/EP0635142A1/en
Priority to JP5517944A priority patent/JPH08500468A/en
Publication of WO1993021553A1 publication Critical patent/WO1993021553A1/en
Priority to US08/318,665 priority patent/US5572543A/en

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/002—Optical devices or arrangements for the control of light using movable or deformable optical elements the movement or the deformation controlling the frequency of light, e.g. by Doppler effect
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
    • G02B26/0841—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting element being moved or deformed by electrostatic means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
    • G02B26/085—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting means being moved or deformed by electromagnetic means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
    • G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
    • G02B26/0858—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting means being moved or deformed by piezoelectric means
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
    • G02B5/0825—Multilayer mirrors, i.e. having two or more reflecting layers the reflecting layers comprising dielectric materials only
    • G02B5/0833—Multilayer mirrors, i.e. having two or more reflecting layers the reflecting layers comprising dielectric materials only comprising inorganic materials only
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
    • G02B5/085—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal
    • G02B5/0858—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal the reflecting layers comprising a single metallic layer with one or more dielectric layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/105—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H01S3/121—Q-switching using intracavity mechanical devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/025—Constructional details of solid state lasers, e.g. housings or mountings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0602—Crystal lasers or glass lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
    • H01S3/09415—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/023—Mount members, e.g. sub-mount members
    • H01S5/02325—Mechanically integrated components on mount members or optical micro-benches
    • H01S5/02326—Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar
    • H01S5/4031—Edge-emitting structures
    • H01S5/4062—Edge-emitting structures with an external cavity or using internal filters, e.g. Talbot filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/42—Arrays of surface emitting lasers

Definitions

  • the invention relates to a laser system with one or more actively controlled laser mirrors in accordance with the generic term of claim 1.
  • Such laser systems are known from the prior art. They are based essentially on the use of electrostrictive materials, such as piezoceramics for moving laser mirrors. Piezo actuators of this type have considerable disadvantages, however, because the piezo ceramics are not free of hysteresis and, on the other hand, they usually require high voltage for actuation, and thirdly, the integration and processing of ceramic elements in the manufacture of such laser systems is relatively complex .
  • Essential manipulation variables are, for example, the tilting of the mirror or the translation along the optical axis.
  • these known systems require the integration of very different materials, so that monolithic production is impossible, and on the other hand, piezoceramics have disadvantages with regard to their mechanical dimensions and the necessary high voltages.
  • piezoceramics have resonance frequencies in the range of typically 100 kHz, so that modulation of piezoceramics beyond this frequency value is not possible or is possible only with great difficulty. It should also be mentioned that self-destruction of the ceramic structure generally occurs even with modulations in the region of the resonance frequency.
  • the laser mirrors according to the prior art usually have a plurality of dielectric layers vapor-deposited on a glass substrate with different refractive indices in alternating order.
  • the layer thicknesses are to be designed as a function of the wavelength so that the multibeam reflection occurring at the interfaces of the layers leads to the desired reflectance by interference. This results in typical layer thicknesses which are about a quarter of the light wavelength ( ⁇ / 4).
  • ⁇ / 4 quarter of the light wavelength
  • such a mirror with a glass substrate cannot be miniaturized without further and also has a relatively large, inert mass, so that it cannot be moved very quickly.
  • such mirrors are relatively cost-intensive components, since the substrates have to be polished, vapor-deposited and mounted or held individually to a high optical quality.
  • Frequency modulation of the laser radiation can thus be carried out, for example, or the laser can be switched on or off in the event of a slight tilting of the mirror, which, with suitable control, leads to the generation of so-called giant pulses (Q switching) of very high peak power.
  • DE-PS 3925201 by the applicant discloses a diode-pumped, miniaturized solid-state laser on an optical bench made of silicon, as a result of which a compact microsystem can be implemented.
  • the present invention has for its object to provide a laser system of the type mentioned, which allows rapid modulation of small laser mirrors, these mirrors are designed so that they allow economical production in large quantities.
  • a miniaturized mirror is to be created which, in addition to the semiconductor substrate (silicon), no longer has any other substrate materials, in certain embodiments can be deflected micromechanically, can execute very fast movements at high frequencies and can be used as adaptive mirror optics .
  • FIG. 1 shows a schematic diagram of an exemplary embodiment for a semiconductor laser with micromechanically held mirrors for fast frequency modulation
  • FIG. 2 shows a schematic diagram of an exemplary embodiment for a diode-pumped solid-state laser with a micromechanically mounted mirror for fast frequency modulation
  • FIG. 3 shows a schematic image of an embodiment of a micromechanically supported laser mirror with a glass plate as a mirror substrate
  • FIG. 4 shows a schematic image of an embodiment for a micromechanically held laser mirror in a top view, the dielectric mirror being produced without a mirror substrate,
  • FIG. 4a shows a schematic image of a cross section through a dielectric multilayer system before the silicon substrate is thinned
  • 4b is a schematic image of a coating of a laser mirror with locally different reflection properties for forming a so-called Gaussian mirror
  • 5 shows a detail sketch to illustrate the micromechanical manipulation devices of the laser mirror in supervision, the movement taking place perpendicularly thereto,
  • 5a is a schematic image in plan view of an embodiment of a movable mirror for tilting movements
  • 5b shows a schematic image for an exemplary embodiment of an adaptive mirror with adjustable curvature of the reflecting membrane by targeted application of negative or positive pressure in the pressure chamber
  • FIG. 6 shows a further detail sketch for the construction of a micromechanical manipulation device
  • FIG. 7 shows a schematic image of a further embodiment of a micromechanically held laser mirror in the plane of the substrate with elements for beam deflection (so-called “folded resonator”), with several laser systems being arranged in terms of area.
  • the laser mirrors according to the prior art are generally very much larger than the other elements of the laser and, moreover, have to be optically polished and coated individually and mechanically held.
  • a micromechanically produced, movable mirror 20 is used which, on the one hand, is not significantly larger in terms of area and volume than the laser diode 1 shown here, on the other hand is manufactured in large numbers using conventional wafer technology and also can also be arranged movably with a suitable shape.
  • the detailed description and configuration of this mirror 20 will be dealt with in the description of FIGS. 5 and 5, in this application the mirror can be deflected in the longitudinal direction, so that the resonator length can thereby be actively set, which in a frequency modulation of the Laser radiation results.
  • the laser can be switched on and off or also switched to quality if the laser mirror is shaped in such a way that the mirror surface is tilted relative to the surface 7 of the semiconductor laser or the semiconductor laser diode 1 by means of micromechanical control.
  • Such mirrors 20, which have a reduced manufacturing accuracy, can be installed without any problems if the mirror 20 is adjusted and subsequently fixed by micromechanically actuating the mirror 20 after installation. Further explanations are given below - in order to avoid repetitions - in the description of FIGS. 5 and 6.
  • Fig. 2 illustrates in an analogous manner a solid-state laser pumped by laser diodes with the proposed mirror arrangement 20, which has the same properties as described.
  • all elements of the laser which have similar mechanical dimensions to the mirror arrangement 20, are mounted on a common base.
  • the semiconductor laser 1 is mounted on egg ner heat sink 2.
  • the laser radiation is via a coupling optics 7 in a solid state laser stable 8 - e.g. Nd: YAG - focused, one end of which is provided, for example, with a coating 9 which is highly transmissive for the laser diode radiation and highly reflective for the solid-state laser radiation.
  • the coating 10 is anti-reflective for the solid-state laser radiation, so that a laser resonator for the solid-state laser radiation is formed between the mirror layer 9 and the coating of the micromechanical mirror 20.
  • the properties of frequency modulation, switching on and off and quality switching are given here, as is active adjustment of the mirror 20.
  • FIG. 3 shows an embodiment of a micromechanical laser mirror which consists of an anisotropically etched semiconductor substrate 51, which is contacted with a mirror substrate 52.
  • the mirror substrate 52 is coated on one side with a partially reflecting mirror layer 53 and on the back with an anti-reflective layer 54 for the laser wavelength.
  • 4 shows a mirror design with a so-called free-floating mirror layer without a substrate. This embodiment can also be used well in the present case, since a particularly simple construction and a small moving mass can be achieved by omitting the substrate 52.
  • the mirror consists of a highly polished silicon substrate of the quality customary in microelectronics with the crystal orientation ⁇ 100> or ⁇ 110> - without any possibility of movement which can be predetermined from the outside.
  • Other single-crystalline substrates such as GaAs, InP or quartz can also be used in principle.
  • This substrate is provided with suitable multilayer dielectric layers. Coatings made of silicon dioxide (SiO 2) and silicon nitride (i 3 N-) are particularly suitable, since they are very well compatible with standard silicon technology. Layer sequences of SiC and TiO «are also possible. Layers of this type can be produced, for example, by deposition from the gas phase (CVD, LPCVD) or with plasma support (PECVD).
  • CVD gas phase
  • PECVD plasma support
  • Evaporation and sputtering is also possible.
  • the thicknesses and the number of individual layers are calculated according to the desired optical properties (reflection, transmission). They typically move at ⁇ / 4 (approx. 100 to 200 nm for visible light). 4a thus illustrates a coating step on a greatly enlarged scale.
  • the silicon substrate in the active mirror area is completely removed by etching, so that the dielectric layer package acts as a mirror in a floating manner (FIG. 4).
  • This can be done with conventional wet chemical etching solutions, e.g. KOH.
  • the reflective property of the mirror can be designed to be variable over its surface in order to eliminate or at least considerably minimize undesirable diffraction effects.
  • the reflection properties are to be varied according to a Gaussian function (Gaussian mirror).
  • Gaussian mirror By incorporating the microelectronic manufacturing techniques, such as, for example, lithography, selective wet chemical or dry etching processes, it is possible to produce such profiles economically by appropriately designing the multi-layer systems with locally different layer thicknesses.
  • FIG. 4b An exemplary embodiment is illustrated in FIG. 4b.
  • 5 and 6 illustrate the detailed structure of the mirror as used in the arrangements according to FIGS. 1 and 2.
  • 5 shows this mirror in a top view.
  • Silicon substrates can, for example, be etched in such a way that there is a small silicon area on movable suspension lugs, which either carries the mirror substrate according to FIG. 3, or is a freely floating mirror layer according to FIG. 4. Due to the elastic suspension, this silicon surface can now be translated or tilted anywhere, depending on the arrangement and control by the actuators.
  • the embodiment sketched in FIG. 5 shows an arrangement for parallel deflection, for example for frequency modulation of the laser used. In this case, e.g. B. a highly symmetrical, diagonal arrangement of the bending beams can be selected.
  • the counter electrode on the lower cover wafer is not divided here.
  • an arrangement is obtained according to the same principle which is suitable for tilting movements of the mirror, for example in order to implement a Q-switching of the laser resonator or an adjustment of the mirror element.
  • the suspension can be selected in the form of two torsion bars. In this case, the electrode surfaces are divided into two separate halves, which are controlled independently of one another.
  • FIG. 6 shows this mirror in section and illustrates the control and the structure of the actuators. It can be clearly seen that between the elastic suspension beams and the mirror layer there is an electrode on the upper wafer, which is opposite an opposing electrode separated by an air gap. Are charges on the electrodes applied, this leads, depending on the charge sign, to an attraction or repulsion of the electrodes and thus - depending on the activation of the entirety of the electrodes and the arrangement of the bending beams, to a translational movement or to a tilting of the mirrors. If the same charge is applied to all electrodes and counter-electrodes, a uniform translation results. If the load is different, it tilts. The tilt can be generated particularly efficiently in a design with torsion bars.
  • the mirror is periodically translated.
  • alternating voltage alternating voltage
  • the mirror By tilting, the mirror can either be adjusted so that the optimal operating point of the laser system is set - which allows a lower requirement for assembly accuracy - or the mirror is periodically tilted in such a way that the laser is switched off from the optimum working point by misalignment of the mirror . If this is carried out with a suitable periodicity and a suitable clock ratio, this leads to the known phenomenon of the giant pulse generation of the laser (Q or Q circuit).
  • the mirrors described here are designed in an etching process in such a way that the optically active region is suspended in a freely movable manner on thin bending beams made of silicon or a suitable thin film. For reasons of integration, it makes sense to use electrostatics to apply the force.
  • the silicon substrate is electrically contacted so that the mirror represents an electrode of a capacitor arrangement.
  • This unit is connected to a second silicon substrate in which a continuous opening for the transmission of the laser beam is machined into it. Furthermore, a shallow depression is provided, which defines the electrode distance from the movable part and thus also the freedom of movement of the mirror. Capacitor counter electrodes are applied within this recess.
  • the mirror is moved electrostatically by applying an external voltage to the electrodes.
  • electrostatics other force principles can also be used, for example piezoelectric or magnetics.
  • a correspondingly small control element or a permanent magnet can be added to the mirror arrangement.
  • the base mirror element is connected to a transparent substrate - for example glass - so that a closed cavity is created which is only connected to an external pressure reservoir or a pump by a selectively controllable channel.
  • the laser mirrors proposed here can be produced using the methods of microsystem technology in such a way that their dimensions are in the order of magnitude of modern laser-active elements in the small and medium power range (laser electrodes typically 300 ⁇ m x 500 ⁇ m x 30 ⁇ m, solid-state lasers typical) 500 ⁇ m x 1 mm x 1 mm).
  • piezoelectrics or magnetics can also be used. This can be a corresponding small control element, or a permanent magnet can be added to the mirror arrangement.
  • FIG. 7 shows a preferred embodiment of an arrangement in which two-dimensional arrays of laser systems with micromechanically manipulable mirrors are produced.
  • an array of semiconductor laser electrodes with micromechanically manipulable mirrors is considered.
  • Solid state lasers pumped by laser diodes can also be produced in an analogous manner.
  • arrays of micromechanically manipulable laser mirrors 160 are etched from a silicon substrate and correspondingly optically coated, so that a two-dimensional arrangement of mirrors is distributed at regular intervals with corresponding control elements over the silicon wafer surface.
  • the mirror and the mirror control can also be made of two silicon wafers which are contacted with one another, so that the mirror control is positioned exactly with respect to the mirror elements.
  • the wafer 150 - provided with a dielectric coating 120 - is positioned exactly in relation to a second wafer 110, on which there is a two-dimensional array arrangement of laser diodes 140 and beam envelope elements 130 at equally regular intervals.
  • This wafer 110 can be made, for example, of silicon, in which the beam deflection elements 140 are etched and provided with a reflecting mirror layer 170, and on which the diodes 130, which are mostly made of GaAs, are correspondingly precisely mounted.
  • the wafer 110 can, however, also consist of a monolithic GaAs arrangement in which the laser diodes are structured and etched accordingly, just like the beam deflection elements 140.
  • This wafer 110 is in turn connected to a cooling unit 100 which, for example, consists of silicon-based microchannel coolers .
  • the radiation from the laser diodes emitted parallel to the wafer surface 110 is now deflected via the beam deflection elements 140 such that it is perpendicular to the
  • the wafer surface of the wafer 150 falls onto the micromechanically movable mirror, from where it is partially reflected, partially emerges as laser radiation 170 perpendicular to the mirror surface.
  • Such an arrangement enables the two-dimensional array formation of individual laser diodes, which can be tuned in frequency, for example, but also of laser diodes which can be quickly modulated in amplitude or frequency, Q-switched laser diodes or the corresponding control of amplitude, frequency or quality of with Pumped solid-state lasers.
  • Manufacturing is easy with conventional batch technology, since only several wafers have to be etched and structured in a known manner, which are then positioned and connected to one another as a whole. A single stage or individual connection of elements is not required here.

Abstract

The invention concerns a laser system with one or more actively controlled mirrors which are manufactured using micro-engineering techniques and are equipped with a manipulation device enabling small laser mirrors to be oscillated rapidly. These mirrors are designed in such a way that they can be manufactured cheaply and in large numbers. Embodiments of the invention are described, and illustrated in the drawings.

Description

Lasersystem mit mikromechanisch bewegten SpiegelLaser system with micromechanically moved mirrors
Die Erfindung bezieht sich auf ein Lasersystem mit einem oder mehreren aktiv kontrollierten Laserspiegeln gemäß dem Gattungsbegriff des Anspru¬ ches 1.The invention relates to a laser system with one or more actively controlled laser mirrors in accordance with the generic term of claim 1.
Solche Lasersysteme sind aus dem Stand der Technik bekannt. Sie beruhen im wesentlichen auf der Verwendung elektrostriktiver Materialien, wie etwa Piezokeramiken zur Bewegung von Laserspiegeln. Solche Piezoaktuato- ren sind jedoch mit erheblichen Nachteilen behaftet, denn die Piezokera¬ miken sind nicht hysteresefrei und zum anderen benötigen sie üblicher¬ weise zur Ansteuerung eine Hochspannung und zum dritten ist die Integra¬ tion und Bearbeitung von Keramikelementen bei der Herstellung solcher Lasersysteme relativ aufwendig.Such laser systems are known from the prior art. They are based essentially on the use of electrostrictive materials, such as piezoceramics for moving laser mirrors. Piezo actuators of this type have considerable disadvantages, however, because the piezo ceramics are not free of hysteresis and, on the other hand, they usually require high voltage for actuation, and thirdly, the integration and processing of ceramic elements in the manufacture of such laser systems is relatively complex .
Wesentliche Manipulationsgrößen sind hierbei etwa die Verkippung des Spiegels oder die Translation entlang der optischen Achse..Zum einen verlangen diese bekannten Systeme die Integration sehr unterschiedlicher Materialien, so daß eine monolithische Fertigung ausgeschlossen ist, zum anderen weisen Piezokerami en Nachteile bezüglich ihrer mechanischen Ab¬ messung und der notwendigen hohen Spannungen auf. Hinzu kommt noch, daß Piezokeramiken Resonanzfrequenzen im Bereich von typisch 100 kHz aufwei¬ sen, so daß eine Modulation von Piezokeramiken über diesen Frequenzwert hinaus nicht oder nur sehr schwer möglich ist. Zu erwähnen ist noch, daß bereits bei Modulationen im Bereich der Resonanzfrequenz im allgemeinen eine Selbstzerstörung der Keramikstruktur auftritt.Essential manipulation variables are, for example, the tilting of the mirror or the translation along the optical axis. On the one hand, these known systems require the integration of very different materials, so that monolithic production is impossible, and on the other hand, piezoceramics have disadvantages with regard to their mechanical dimensions and the necessary high voltages. In addition, piezoceramics have resonance frequencies in the range of typically 100 kHz, so that modulation of piezoceramics beyond this frequency value is not possible or is possible only with great difficulty. It should also be mentioned that self-destruction of the ceramic structure generally occurs even with modulations in the region of the resonance frequency.
Die Laserspiegel nach dem Stand der Technik weisen üblicherweise mehrere auf einem Glassubstrat aufgedampfte dielektrische Schichten mit unter¬ schiedlichen Brechungsindizes in abwechselnder Reihenfolge auf. Die Schichtdicken sind dabei in Abhängigkeit von der Wellenlänge so auszule¬ gen, daß die an den Grenzflächen der Schichten auftretende Vielstrahlre flexion durch Interferenz zu dem gewünschten Reflexionsgrad führt. Dies ergibt typische Schichtdicken, die bei etwa einem Viertel der Lichtwel¬ lenlänge (λ/4) liegen. Ein solcher Spiegel mit Glassubstrat ist aber nicht ohne weiteras miniaturisierbar und hat auch eine relativ große, träge Masse, so daß er nicht sehr schnell bewegt werden kann. Außerdem sind solche Spiegel relativ kostenintensive Bauteile, da die Substrate einzeln auf hohe optische Qualität poliert, bedampft und montiert oder gehaltert werden müssen.The laser mirrors according to the prior art usually have a plurality of dielectric layers vapor-deposited on a glass substrate with different refractive indices in alternating order. The layer thicknesses are to be designed as a function of the wavelength so that the multibeam reflection occurring at the interfaces of the layers leads to the desired reflectance by interference. This results in typical layer thicknesses which are about a quarter of the light wavelength (λ / 4). However, such a mirror with a glass substrate cannot be miniaturized without further and also has a relatively large, inert mass, so that it cannot be moved very quickly. In addition, such mirrors are relatively cost-intensive components, since the substrates have to be polished, vapor-deposited and mounted or held individually to a high optical quality.
Moderne Laser zeichnen sich aber insbesondere durch immer kleinere Ab¬ messungen bei ausgesprochen hoher Leistungsdichte aus. Am bekanntesten sind hierbei die Halbleiterlaser sowie die von Halbleiterlaser gepumpten Festkörperlaser. Für den Betrieb solcher Laser sind Spiegel mit sehr gu¬ ten optischen Eigenschaften und genau definiertem Reflexionsgrad erfor¬ derlich. In den meisten Fällen werden die Spiegel in "monolithischer" Bauweise mittels einer dielektrischen Schichtenfolge direkt auf das la¬ seraktive Bauelement aufgebracht. Für eine Reihe von Anwendungen ist es jedoch von Vorteil, wenn mindestens ein Spiegel vom laseraktiven Medium getrennt angeordnet ist. Zum einen erhält man hierbei in vielen Fällen eine bessere Strahlungsqua itat, zum anderen kann man diesen separaten Spiegel beweglich oder justierbar gestalten. Damit kann beispielsweise eine Frequenzmodulation der Laserstrahlung vorgenommen werden oder im Falle einer leichten Verkippung des Spiegels der Laser ein- oder ausge¬ schaltet werden, was bei geeigneter Ansteuerung zur Erzeugung von soge¬ nannten Riesenimpulsen (Q-Schaltung) sehr hoher Spitzenleistung führt.However, modern lasers are characterized in particular by ever smaller dimensions with an extremely high power density. The best known are the semiconductor lasers and the solid-state lasers pumped by semiconductor lasers. Mirrors with very good optical properties and a precisely defined degree of reflection are required for the operation of such lasers. In most cases, the mirrors are applied directly to the laser-active component in a "monolithic" manner by means of a dielectric layer sequence. For a number of applications, however, it is advantageous if at least one mirror is arranged separately from the laser-active medium. On the one hand you get a better radiation quality in many cases, on the other hand you can make this separate mirror movable or adjustable. Frequency modulation of the laser radiation can thus be carried out, for example, or the laser can be switched on or off in the event of a slight tilting of the mirror, which, with suitable control, leads to the generation of so-called giant pulses (Q switching) of very high peak power.
Durch die zunehmende Forderung weiterer Miniaturisierung von Lasersyste¬ men werden aber auch die Anforderungen an die Kompaktheit von Laserspie¬ geln immer höher. Durch die DE-PS 3925201 der Anmelderin ist ein dio¬ dengepumpter, miniaturisierter Festkörperlaser auf einer optischen Bank aus Silizium bekannt, wodurch ein kompaktes Mikrosystem realisierbar ist.However, due to the increasing demand for further miniaturization of laser systems, the requirements for the compactness of laser mirrors are becoming ever higher. DE-PS 3925201 by the applicant discloses a diode-pumped, miniaturized solid-state laser on an optical bench made of silicon, as a result of which a compact microsystem can be implemented.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Lasersystem der eingangs genannten Art zu schaffen, das eine schnelle Modulation von kleinen Laserspiegeln erlaubt, wobei diese Spiegel so konzipiert sind, daß sie eine wirtschaftliche Fertigung in großen Stückzahlen erlauben. Insbesondere ist in einer besonderen Ausführungsform ein miniaturisier¬ ter Spiegel zu schaffen, der neben dem Halbleitersubstrat (Silizium) keine anderen Substratmaterialien mehr aufweist, in bestimmten Ausfüh¬ rungsformen mikromechanisch auslenkbar ist, sehr schnelle Bewegungen bei hohen Frequenzen ausführen kann und als adaptive Spiegeloptik einsetzbar Ist.The present invention has for its object to provide a laser system of the type mentioned, which allows rapid modulation of small laser mirrors, these mirrors are designed so that they allow economical production in large quantities. In particular, in a special embodiment, a miniaturized mirror is to be created which, in addition to the semiconductor substrate (silicon), no longer has any other substrate materials, in certain embodiments can be deflected micromechanically, can execute very fast movements at high frequencies and can be used as adaptive mirror optics .
Diese Aufgabe wird durch die im Anspruch 1 aufgezeigten Maßnahmen ge¬ löst. In den Unteransprüchen sind Ausgestaltungen und Weiterbildungen angegeben und in der nachfolgenden Beschreibung sind Ausführungsbeispie¬ le erläutert und in den Figuren der Zeichnung skizziert. Es zeigenThis object is achieved by the measures indicated in claim 1. Refinements and developments are specified in the subclaims and exemplary embodiments are explained in the following description and outlined in the figures of the drawing. Show it
Fig. 1 ein Schemabild eines Ausführungsbeispieles für einen Halbleiter¬ laser mit mikromechanisch gehalterte Spiegel zur schnellen Fre¬ quenzmodulation,1 shows a schematic diagram of an exemplary embodiment for a semiconductor laser with micromechanically held mirrors for fast frequency modulation,
Fig. 2 ein Schemabild eines Ausführungsbeipleles für einen diodenge¬ pumpten Festkörperlaser mit mikromechanisch gehaltertem Spiegel zur schnellen Frequenzmodulation,2 shows a schematic diagram of an exemplary embodiment for a diode-pumped solid-state laser with a micromechanically mounted mirror for fast frequency modulation,
Fig. 3 ein Schemabild einer Ausführungsform eines mikromechanisch ge¬ halterten Laserspiegels mit einem Glasplättchen als Spiegelsub¬ strat,3 shows a schematic image of an embodiment of a micromechanically supported laser mirror with a glass plate as a mirror substrate,
Fig. 4 ein Schemabild einer Ausführungsform für einen mikromechanisch gehalterten Laserspiegel in der Draufsicht, wobei der dielektri¬ sche Spiegel ohne Spiegelsubstrat hergestellt ist,4 shows a schematic image of an embodiment for a micromechanically held laser mirror in a top view, the dielectric mirror being produced without a mirror substrate,
Fig. 4a ein Schemabild eines Querschnittes durch ein dielektrisches Mul- tischichtsystem vor dem Abdünnen des Siliziumsubstrates,4a shows a schematic image of a cross section through a dielectric multilayer system before the silicon substrate is thinned,
Fig. 4b ein Schemabild einer Beschichtung eines Laserspiegels mit lokal unterschiedlichen Reflexionseigenschaften zur Formung eines sog. Gauß'schen Spiegels, Fig. 5 eine Ausschnittskizze zur Verdeutlichung der mikromechanischen Manipulationsvorrichtungen des Laserspiegels in Aufsicht, wobei die Bewegung senkrecht hierzu erfolgt,4b is a schematic image of a coating of a laser mirror with locally different reflection properties for forming a so-called Gaussian mirror, 5 shows a detail sketch to illustrate the micromechanical manipulation devices of the laser mirror in supervision, the movement taking place perpendicularly thereto,
Fig. 5a ein Schemabild in der Draufsicht auf ein Ausführungsbeispiel ei¬ nes beweg ichen Spiegels für Kippbewegungen,5a is a schematic image in plan view of an embodiment of a movable mirror for tilting movements,
Fig. 5b ein Schemabild für ein Ausführungbeispiel eines adaptiven Spie¬ gels mit einstellbarer Krümmung der reflektierenden Membran durch gezieltes Anlegen von Unter- oder Überdruck in der Druck¬ kammer,5b shows a schematic image for an exemplary embodiment of an adaptive mirror with adjustable curvature of the reflecting membrane by targeted application of negative or positive pressure in the pressure chamber,
Fig. 6 eine weitere Ausschnittskizze zum Aufbau einer mikromechanischen Manipulationsvorrichtung,6 shows a further detail sketch for the construction of a micromechanical manipulation device,
Fig. 7 ein Schemabild einer weiteren Ausführungsform eines mikromecha¬ nisch gehalterten Laserspiegels in der Ebene des Substrates mit Elementen zur Strah um!enkung (sog. "gefalteter Resonator"), wo¬ bei mehrere Lasersysteme flächenmäßig angeordnet sind.7 shows a schematic image of a further embodiment of a micromechanically held laser mirror in the plane of the substrate with elements for beam deflection (so-called "folded resonator"), with several laser systems being arranged in terms of area.
Die Laserspiegel nach dem Stand der Technik sind allgemein sehr viel größer, als die sonstigen Elemente des Lasers und müssen außerdem ein¬ zeln optisch poliert und beschichtet sowie mechanisch gehaltert werden. In dem Ausführungsbeispiel gemäß Fig. 1 wird ein mikromechanisch herge¬ stellter, bewegbarer Spiegel 20 verwendet, welcher zum einen flächen- und volumenmäßig nicht wesentlich größer ist als die hier eingezeichnete Laserdiode 1, zum anderen in großen Stückzahlen in herkömmlicher Wafer- technologie gefertigt und außerdem auch noch bei geeigneter Ausformung bewegbar angeordnet werden kann. Auf die detaillierte Beschreibung bzw. Ausgestaltung dieses Spiegels 20 wird bei der Beschreibung der Fig. 5 und 5 eingegangen, in diesem Anwendungsfall kann der Spiegel in longitu- dinaler Richtung ausgelenkt werden, so daß hierdurch die Resonatorlänge aktiv einstellbar ist, was in einer Frequenzmodulation der Laserstrah¬ lung resultiert. In gleicher Anordnung kann der Laser ein- und ausgeschaltet oder auch gütegeschaltet werden, wenn der Laserspiegel so ausgeformt ist, daß ein Verkippung der Spiegelfläche relativ zur Fläche 7 des Halbleiterlasers bzw. der Halble1ter-Laserd1ode 1 durch mikromechanische Ansteuerung er¬ folgt. Problemlos können solche Spiegel 20, die eine verminderte Ferti¬ gungsgenauigkeit aufweisen, montiert werden, wenn durch mikromechanisch Ansteuerung des Spiegels 20 nach der Montage, letzterer einjustiert und anschließend fixiert wird. Nähere Erläuterungen hierzu werden nachfol¬ gend - um Wiederholungen zu vermeiden - in der Beschreibung zu den Fig. 5 und 6 gegeben.The laser mirrors according to the prior art are generally very much larger than the other elements of the laser and, moreover, have to be optically polished and coated individually and mechanically held. In the exemplary embodiment according to FIG. 1, a micromechanically produced, movable mirror 20 is used which, on the one hand, is not significantly larger in terms of area and volume than the laser diode 1 shown here, on the other hand is manufactured in large numbers using conventional wafer technology and also can also be arranged movably with a suitable shape. The detailed description and configuration of this mirror 20 will be dealt with in the description of FIGS. 5 and 5, in this application the mirror can be deflected in the longitudinal direction, so that the resonator length can thereby be actively set, which in a frequency modulation of the Laser radiation results. In the same arrangement, the laser can be switched on and off or also switched to quality if the laser mirror is shaped in such a way that the mirror surface is tilted relative to the surface 7 of the semiconductor laser or the semiconductor laser diode 1 by means of micromechanical control. Such mirrors 20, which have a reduced manufacturing accuracy, can be installed without any problems if the mirror 20 is adjusted and subsequently fixed by micromechanically actuating the mirror 20 after installation. Further explanations are given below - in order to avoid repetitions - in the description of FIGS. 5 and 6.
Die Fig. 2 veranschaulicht in analoger Weise einen durch Laserdioden ge pumpten Festkörperlaser mit der vorgeschlagenen Spiegelanordnung 20, welche dieselben Eigenschaften wie beschrieben aufweist. Bei diesem Aus führungsbeispiel werden hier alle Elemente des Lasers, welche ähnliche mechanische Abmessungen aufweisen, wie die Spiegelanordnung 20, auf ei¬ ner gemeinsamen Basis montiert werden. Der Halbleiterlaser 1 ist auf ei ner Wärmesenke 2 montiert. Die Laserstrahlung wird über eine Ankoppelop tik 7 in einen Festkörperlaserkrlstall 8 - z.B. Nd:YAG - fokussiert, dessen eine Stirnseite beispielsweise mit einem Coating 9 versehen ist, welches hochtransmittierend für die Laserdiodenstrahlung und hochreflek tierend für die Festkörperlaserstrahlung ist. Das Coating 10 ist antire flektlerend für die Festkörperlaserstrahlung, so daß sich zwischen Spie gelschicht 9 und der Beschichtung des mikromechanischen Spiegels 20 ein Laserresonator für die Festkörperlaserstrahlung ausbildet. Die Eigen¬ schaften des Frequenzmodulierens, An- und Ausschalten sowie das Güte¬ schalten sind hier ebenso gegeben, wie eine aktive Justage des Spiegels 20.Fig. 2 illustrates in an analogous manner a solid-state laser pumped by laser diodes with the proposed mirror arrangement 20, which has the same properties as described. In this exemplary embodiment, all elements of the laser, which have similar mechanical dimensions to the mirror arrangement 20, are mounted on a common base. The semiconductor laser 1 is mounted on egg ner heat sink 2. The laser radiation is via a coupling optics 7 in a solid state laser stable 8 - e.g. Nd: YAG - focused, one end of which is provided, for example, with a coating 9 which is highly transmissive for the laser diode radiation and highly reflective for the solid-state laser radiation. The coating 10 is anti-reflective for the solid-state laser radiation, so that a laser resonator for the solid-state laser radiation is formed between the mirror layer 9 and the coating of the micromechanical mirror 20. The properties of frequency modulation, switching on and off and quality switching are given here, as is active adjustment of the mirror 20.
In der Fig. 3 ist eine Ausführungsform eines mikromechanischen Laser¬ spiegels skizziert, der aus einem anisotrop geätzten Halbleitersubstrat 51 besteht, welches mit einem SpiegelSubstrat 52 kontaktiert Ist. Das Spiegelsubstrat 52 ist einseitig mit einer teilreflektierenden Spiegel- schicht 53 und rückseitig mit einer Antlreflexschicht 54 für die Laser¬ wellenlänge beschichtet. In der Fig.4 ist eine Spiegelausführung mit sogenannter freischwebender Spiegelschicht ohne Substrat gezeigt. Diese Ausführungsform kann auch im hier vorliegenden Falle gut eingesetzt werden, da durch Weglassen des Substrates 52 ein besonders einfacher Aufbau und eine geringe bewegte Masse realisiert werden kann.3 shows an embodiment of a micromechanical laser mirror which consists of an anisotropically etched semiconductor substrate 51, which is contacted with a mirror substrate 52. The mirror substrate 52 is coated on one side with a partially reflecting mirror layer 53 and on the back with an anti-reflective layer 54 for the laser wavelength. 4 shows a mirror design with a so-called free-floating mirror layer without a substrate. This embodiment can also be used well in the present case, since a particularly simple construction and a small moving mass can be achieved by omitting the substrate 52.
In seiner einfachsten Form besteht der Spiegel - ohne von außen vorgeb¬ bare Bewegungsmöglichkeit - aus einem hochpolierten Siliziumsubstrat der in der Mikroelektronik üblichen Qualität mit der KristallOrientierung <100> oder <110>. Auch andere einkristalline Substrate wie z.B. GaAs, InP oder Quarz sind prinzipiel verwendbar. Dieses Substrat wird mit ge¬ eigneten mehrlagigen dielektrischen Schichten versehen. Insbesondere bieten sich Beschichtungen aus Siliziumdioxid (SiO«) und Siliziumni¬ trit ( i3N-) an, da sie mit der Standard-Siliziumtechnologie sehr gut kompatibel sind. Aber auch Schichtenfolgen von SiC und TiO« kommen unter anderem in Frage. Schichten dieser Art können beispielswei¬ se durch Abscheidung aus der Gasphase (CVD, LPCVD) oder mit Plasmaunter¬ stützung (PECVD) hergestellt werden. Auch Aufdampfen und Sputtern ist möglich. Die Dicken sowie die Anzahl der Einzelschichten werden nach den gewünschten optischen Eigenschaften (Reflexion, Transmission) berechnet. Sie bewegen sich typischerweise bei λ/4 (ca. 100 bis 200 nm für sicht¬ bares Licht). Die Fig. 4a veranschaulicht so einen Beschlchtungsschritt in einem stark vergrößerten Maßstab.In its simplest form, the mirror consists of a highly polished silicon substrate of the quality customary in microelectronics with the crystal orientation <100> or <110> - without any possibility of movement which can be predetermined from the outside. Other single-crystalline substrates such as GaAs, InP or quartz can also be used in principle. This substrate is provided with suitable multilayer dielectric layers. Coatings made of silicon dioxide (SiO 2) and silicon nitride (i 3 N-) are particularly suitable, since they are very well compatible with standard silicon technology. Layer sequences of SiC and TiO «are also possible. Layers of this type can be produced, for example, by deposition from the gas phase (CVD, LPCVD) or with plasma support (PECVD). Evaporation and sputtering is also possible. The thicknesses and the number of individual layers are calculated according to the desired optical properties (reflection, transmission). They typically move at λ / 4 (approx. 100 to 200 nm for visible light). 4a thus illustrates a coating step on a greatly enlarged scale.
Nach der Herstellung der optisch aktiven Beschichtung wird das Silizium- substrat im aktiven Spiegelbereich ätztechnisch vollständig entfernt, so daß das dielektrische Schichtpaket freischwebend als Spiegel wirkt (Fig.4). Dies kann mit üblichen naßchemischen Ätzlösungen, wie z.B. KOH, erzielt werden. Durch geeignete Einstellung der schichtkohärenten mechanischen Spannungen kann dafür gesorgt werden, daß diese Schicht hochplan ist.After the production of the optically active coating, the silicon substrate in the active mirror area is completely removed by etching, so that the dielectric layer package acts as a mirror in a floating manner (FIG. 4). This can be done with conventional wet chemical etching solutions, e.g. KOH. By appropriately setting the layer-coherent mechanical stresses, it can be ensured that this layer is highly planar.
Für manche Anwendungen ist es vorteilhaft, daß die Reflexionseigenschaft des Spiegels über seine Fläche variabel gestaltbar ist, um unerwünschte Beugungseffekte zu eliminieren oder zumindest erheblich zu minimieren. Insbesondere gibt es Anwendungen, bei denen die Reflexionseigenschaften gemäß einer Gauß-Funktion variiert werden sollen (Gauß'scher Spiegel). Durch Einbeziehung der mikroelektronischen Fertigungstechniken, wie bei¬ spielsweise Lithographie, selektive naßchemische oder Trocken-Ätzverfah¬ ren, Ist es möglich, solche Profile durch entsprechende Ausgestaltung der VielSchichtensysteme mit örtlich unterschiedlichen Schichtdicken wirtschaftlich herzustellen. Ein Ausführungsbeispiel Ist in der Fig. 4b veranschaulicht.For some applications it is advantageous that the reflective property of the mirror can be designed to be variable over its surface in order to eliminate or at least considerably minimize undesirable diffraction effects. In particular, there are applications in which the reflection properties are to be varied according to a Gaussian function (Gaussian mirror). By incorporating the microelectronic manufacturing techniques, such as, for example, lithography, selective wet chemical or dry etching processes, it is possible to produce such profiles economically by appropriately designing the multi-layer systems with locally different layer thicknesses. An exemplary embodiment is illustrated in FIG. 4b.
Die Fig. 5 und 6 veranschaulichen den detaillierten Aufbau des Spiegels, wie er in den Anordnungen gemäß den Fig. 1 und 2 verwendet wird. Hierbei zeigt die Fig. 5 diesen Spiegel in einer Aufsicht. Siliziumsubstrate können beispielsweise so geätzt werden, daß an beweglichen Aufhängela¬ schen eine kleine Siliziumfläche vorhanden ist, welche entweder das Spiegelsubstrat gemäß Fig. 3 trägt, oder aber eine frei schwebende Spie¬ gelschicht gemäß Fig. 4 ist. Aufgrund der elastischen Aufhängung kann diese Siliziumflache nun je nach Anordnung und Ansteuerung durch die Ak- tuatoren, überall translatiert oder verkippt werden. Das in Fig. 5 skiz¬ zierte Ausführungsbeispiel zeigt eine Anordnung für parallele Auslen¬ kung, beispielsweise zur Frequenzmodulation des verwendeten Lasers. In diesem Fall kann z. B. eine hochgradig symmetrische, diagonale Anordnung der Biegebalken gewählt werden. Die Gegenelektrode am unteren Deckwafer ist hierbei nicht unterteilt. In einer leichten Abwandlung gemäß Fig. 5a ergibt sich nach dem gleichen Prinzip eine Anordnung, die sich für Kipp¬ bewegungen des Spiegels eignet, beispielsweise um eine Güteschaltung des Laserresonators oder eine Justage des Spiegelelementes zu realisieren. Die Aufhängung kann hierbei in Form zweier Torsionsbalken gewählt wer¬ den. In diesem Falle werden die Elektrodenflächen in zwei getrennte Hälften geteilt, die unabhängig voneinander angesteuert werden.5 and 6 illustrate the detailed structure of the mirror as used in the arrangements according to FIGS. 1 and 2. 5 shows this mirror in a top view. Silicon substrates can, for example, be etched in such a way that there is a small silicon area on movable suspension lugs, which either carries the mirror substrate according to FIG. 3, or is a freely floating mirror layer according to FIG. 4. Due to the elastic suspension, this silicon surface can now be translated or tilted anywhere, depending on the arrangement and control by the actuators. The embodiment sketched in FIG. 5 shows an arrangement for parallel deflection, for example for frequency modulation of the laser used. In this case, e.g. B. a highly symmetrical, diagonal arrangement of the bending beams can be selected. The counter electrode on the lower cover wafer is not divided here. In a slight modification according to FIG. 5a, an arrangement is obtained according to the same principle which is suitable for tilting movements of the mirror, for example in order to implement a Q-switching of the laser resonator or an adjustment of the mirror element. The suspension can be selected in the form of two torsion bars. In this case, the electrode surfaces are divided into two separate halves, which are controlled independently of one another.
Die Fig. 6 zeigt diesen Spiegel im Schnitt und verdeutlicht die Ansteue¬ rung und den Aufbau der Aktoren. Es ist deutlich erkennbar, daß zwischen den elastischen Aufhängebalken und der Spiegelschicht je eine Elektrode am oberen Wafer angeordnet ist, welche über einen Luftspalt getrennt ei¬ ner Gegenelektrode gegenüberliegt. Werden Ladungen auf die Elektroden aufgebracht, so führt dies je nach dem Ladungsvorzeichen zu einer Anzie¬ hung oder Abstoßung der Elektroden und somit - je nach Ansteuerung der Gesamtheit der Elektroden und der Anordnung der Biegebalken, zu einer translatorischen Bewegung oder zu einer Verkippung der Spiegel. Wird auf jeweils alle Elektroden und Gegenelektroden jeweils dieselbe Ladung auf¬ gebracht, so ergibt sich eine gleichförmige Translation. Ist die Ladung unterschiedlich, so ergibt sich eine Verkippung. Insbesondere bei einer Konzeption mit Torsionsbalken ist die Verkippung besonders effizient zu erzeugen.6 shows this mirror in section and illustrates the control and the structure of the actuators. It can be clearly seen that between the elastic suspension beams and the mirror layer there is an electrode on the upper wafer, which is opposite an opposing electrode separated by an air gap. Are charges on the electrodes applied, this leads, depending on the charge sign, to an attraction or repulsion of the electrodes and thus - depending on the activation of the entirety of the electrodes and the arrangement of the bending beams, to a translational movement or to a tilting of the mirrors. If the same charge is applied to all electrodes and counter-electrodes, a uniform translation results. If the load is different, it tilts. The tilt can be generated particularly efficiently in a design with torsion bars.
Werden bei einer translatorisehen Verschiebung die Ladungen mit einer schnellen Periodizität aufgebracht (WechselSpannung), so wird der Spie¬ gel periodisch translatiert. Die Translation eines Laser-Resonatorspie¬ gels führt aber wie bekannt zu einer Frequenzänderung des Lasers und ei¬ ne schnelle periodische Translation auch zu einer schnellen Frequenzmo¬ dulation.If the charges are applied with a rapid periodicity (alternating voltage) during a translational shift, the mirror is periodically translated. However, as is known, the translation of a laser resonator mirror leads to a frequency change of the laser and a rapid periodic translation also leads to rapid frequency modulation.
Durch Verkippung kann der Spiegel entweder so justiert werden, daß der optimale Arbeitspunkt des Lasersystems eingestellt wird - was eine ge¬ ringere Anforderung an die Montagegenauigkeit erlaubt - oder der Spiegel wird periodisch so verkippt, daß der Laser vom optimalen Arbeitspunkt durch Dejustage des Spiegels ausgeschaltet wird. Wird dies mit geeigne¬ ter Periodizität und geeignetem Taktverhältnis durchgeführt, so führt dies zum bekannten Phänomen der Riesenpulserzeugung des Lasers (Güte¬ oder Q-Schaltung).By tilting, the mirror can either be adjusted so that the optimal operating point of the laser system is set - which allows a lower requirement for assembly accuracy - or the mirror is periodically tilted in such a way that the laser is switched off from the optimum working point by misalignment of the mirror . If this is carried out with a suitable periodicity and a suitable clock ratio, this leads to the known phenomenon of the giant pulse generation of the laser (Q or Q circuit).
Die hier beschriebenen Spiegel werden ätztechnisch so ausgestaltet, daß der optisch aktive Bereich an dünnen Biegebalken aus Silizium- oder ei¬ nem geeigneten Dünnfilm frei beweglich aufgehängt wird. Aus Integrier- barkeitsgründen bietet es sich an, zur Krafteinleitung die Elektrostatik zu verwenden. Dabei wird das Siliziumsubstrat elektrisch kontaktiert, so daß der Spiegel eine Elektrode einer Kondensatoranordnung darstellt. Diese Einheit wird mit einem zweiten Siliziumsubstrat verbunden, in das eine durchgehende Öffnung zur Transmission des Laserstrahls hineingear¬ beitet ist. Ferner ist eine flache Vertiefung vorgesehen, die den Elek¬ trodenabstand zum beweglichen Teil und damit auch die Bewegungsfreiheit des Spiegels festlegt. Innerhalb dieser Vertiefung sind Kondensator-Ge¬ genelektroden aufgebracht. Diese zwei Substrate werden durch geeignete Verfahren - wie beispielsweise anodisches Bonden oder Si-Si-Bonden - miteinander verbunden. Durch Anlegen einer äußeren Spannung an die Elek¬ troden wird der Spiegel elektrostatisch bewegt. Neben der Elektrostatik können auch andere Kraftprinzipien eingesetzt werden, z.B. die Piezo¬ elektrik oder die Magnetik. Dazu kann ein entsprechend kleines Stellele- ent oder ein Dauermagnet der Spiegelanordnung zugefügt werden.The mirrors described here are designed in an etching process in such a way that the optically active region is suspended in a freely movable manner on thin bending beams made of silicon or a suitable thin film. For reasons of integration, it makes sense to use electrostatics to apply the force. The silicon substrate is electrically contacted so that the mirror represents an electrode of a capacitor arrangement. This unit is connected to a second silicon substrate in which a continuous opening for the transmission of the laser beam is machined into it. Furthermore, a shallow depression is provided, which defines the electrode distance from the movable part and thus also the freedom of movement of the mirror. Capacitor counter electrodes are applied within this recess. These two substrates are connected to one another by suitable methods, such as, for example, anodic bonding or Si-Si bonding. The mirror is moved electrostatically by applying an external voltage to the electrodes. In addition to electrostatics, other force principles can also be used, for example piezoelectric or magnetics. For this purpose, a correspondingly small control element or a permanent magnet can be added to the mirror arrangement.
Eine weitere Möglichkeit die sich aus der Dünnf11m-Anordnung des Spie¬ gels ergibt, ist die gezielte Verwölbung der Spiegelfläche durch Anlegen eines Unter- oder Überdruckes. Damit läßt sich z.B. die Brennweite des Spiegels einstellen, so daß eine gezielte Fokussierung ermöglicht wird. Ein Ausführungsbeispiel hierzu ist in der Fig. 5b skizziert. Das Basis¬ spiegelelement wird mit einem transparenten Substrat - beispielseise Glas - verbunden, so daß ein abgeschlossener Hohlraum entsteht, der le¬ diglich durch einen gezielt ansteuerbaren Kanal mit einem externen Druckvorratsbehälter bzw. einer Pumpe verbunden ist.Another possibility that results from the thin-line arrangement of the mirror is the targeted arching of the mirror surface by applying a negative or positive pressure. This allows e.g. adjust the focal length of the mirror so that targeted focusing is possible. An exemplary embodiment of this is outlined in FIG. 5b. The base mirror element is connected to a transparent substrate - for example glass - so that a closed cavity is created which is only connected to an external pressure reservoir or a pump by a selectively controllable channel.
Damit ist ein Spiegel geschaffen, der aufgrund seiner durch die Bauart bedingten sehr kleinen Masse, sehr schnelle Bewegungen bei hohen Fre¬ quenzen realisieren kann. Aufgrund des fehlenden Substrates im optischen Strahlengang muß keine Entspiegelung der Rückseite durchgeführt werden. Die hier vorgeschlagenen Laserspiegel können mit den Verfahren der Mi- krosystemtechnik so hergestellt werden, daß sie in ihren Ab esssungen in der Größenordnung moderner laseraktiver Elemente im kleinen und mittle¬ ren Leistungsbereich liegen (Laserdloden typisch 300 μm x 500 μm x 30 μm, Festkörperlaser typisch 500 μm x 1 mm x 1 mm).This creates a mirror which, owing to its very small mass due to its design, can implement very fast movements at high frequencies. Due to the lack of a substrate in the optical beam path, no anti-reflective treatment of the rear has to be carried out. The laser mirrors proposed here can be produced using the methods of microsystem technology in such a way that their dimensions are in the order of magnitude of modern laser-active elements in the small and medium power range (laser electrodes typically 300 μm x 500 μm x 30 μm, solid-state lasers typical) 500 μm x 1 mm x 1 mm).
Neben der Elektrostatik können auch andere Kraftprinzipien, wie bei¬ spielsweise Piezoelektrik oder Magnetik eingesetzt werden. Dazu kann ein entsprechendes kleines Stellelemenet, oder ein Dauermagnet der Spiegel- anordnung hinzugefügt werden.In addition to electrostatics, other force principles, such as piezoelectrics or magnetics, can also be used. This can be a corresponding small control element, or a permanent magnet can be added to the mirror arrangement.
Die Fig. 7 zeigt eine bevorzugte Ausführungsform einer Anordnung, bei welcher zweidimensional Arrays von Lasersystemen mit mikromechanisch manipulierbaren Spiegel hergestellt werden. Um das System nicht unnötig komplex darzustellen, wird lediglich ein Array von Halbleiter-Laserdlo¬ den mit mikromechanisch manipulierbaren Spiegeln betrachtet. In analoger Weise können jedoch auch von Laserdioden gepumpte Festkörperlaser herge¬ stellt werden.FIG. 7 shows a preferred embodiment of an arrangement in which two-dimensional arrays of laser systems with micromechanically manipulable mirrors are produced. In order not to represent the system unnecessarily complex, only an array of semiconductor laser electrodes with micromechanically manipulable mirrors is considered. Solid state lasers pumped by laser diodes can also be produced in an analogous manner.
In dieser dargestellten Ausführungsform werden Arrays von mikromecha¬ nisch manipulierbaren Laserspiegeln 160 aus einem Siliziumsubstrat ge¬ ätzt und entsprechend optisch beschichtet, so daß über die Slliziumwa- feroberfläche verteilt eine zweidimensionale Anordnung von Spiegeln in regelmäßigen Abständen mit entsprechenden AnSteuerelementen entsteht. Hierbei können auch die Spiegel und die Spiegelansteuerung aus zwei Si- lizlu wafern gefertigt sein, welche miteinander kontaktiert werden, so daß die Spiegelansteuerung jeweils exakt zu den Spiege elementen posi¬ tioniert ist. Der Wafer 150 - versehen mit einer dielektrischen Be¬ schichtung 120 - wird exakt positioniert in Relation zu einem zweiten Wafer 110, auf welchem sich in ebenso regelmäßigen Abständen eine zwei¬ dimensionale Arrayanordnung von Laserdioden 140 und Strahlum!enkelemen- ten 130 befindet. Dieser Wafer 110 kann beispielsweise aus Silizium be¬ stehen, in welches die Strahlumlenkelemente 140 geätzt und mit einer re¬ flektierenden Spiegelschlcht 170 versehen sind, und auf welchem die zu¬ meist auf GaAs-Basis hergestellten Dioden 130 entsprechend exakt mon¬ tiert sind. Der Wafer 110 kann aber auch aus einer monolithischen GaAs- Anordnung bestehen, in welcher die Laserdioden entsprechend strukturiert und geätzt sind, ebenso wie die Strahlumlenkelemente 140. Dieser Wafer 110 ist nun seinerseits verbunden mit einer Kühleinheit 100, welche z.B. aus auf Siliziumbasis hergestellten Mikrokanalkühlem besteht. Die pa¬ rallel zur Waferflache 110 emittierte Strahlung der Laserdioden wird nun über die Strahlumlenkelemente 140 so umgelenkt, daß sie senkrecht zur Waferoberflache des Wafers 150 auf die mikromechanisch bewegbaren Spie¬ gel fällt, von dort teilweise in sich reflektiert wird, teilweise als Laserstrahlung 170 senkrecht zur Spiegelfläche austritt.In this illustrated embodiment, arrays of micromechanically manipulable laser mirrors 160 are etched from a silicon substrate and correspondingly optically coated, so that a two-dimensional arrangement of mirrors is distributed at regular intervals with corresponding control elements over the silicon wafer surface. Here, the mirror and the mirror control can also be made of two silicon wafers which are contacted with one another, so that the mirror control is positioned exactly with respect to the mirror elements. The wafer 150 - provided with a dielectric coating 120 - is positioned exactly in relation to a second wafer 110, on which there is a two-dimensional array arrangement of laser diodes 140 and beam envelope elements 130 at equally regular intervals. This wafer 110 can be made, for example, of silicon, in which the beam deflection elements 140 are etched and provided with a reflecting mirror layer 170, and on which the diodes 130, which are mostly made of GaAs, are correspondingly precisely mounted. The wafer 110 can, however, also consist of a monolithic GaAs arrangement in which the laser diodes are structured and etched accordingly, just like the beam deflection elements 140. This wafer 110 is in turn connected to a cooling unit 100 which, for example, consists of silicon-based microchannel coolers . The radiation from the laser diodes emitted parallel to the wafer surface 110 is now deflected via the beam deflection elements 140 such that it is perpendicular to the The wafer surface of the wafer 150 falls onto the micromechanically movable mirror, from where it is partially reflected, partially emerges as laser radiation 170 perpendicular to the mirror surface.
Eine solche Anordnung ermöglicht die zweidimensionale Arrayausbildung von einzelnen, beispielsweise in der Frequenz abstimmbaren Laserdioden, aber auch von einzeln in der Amplitude oder in der Frequenz schnell mo¬ dulierbaren Laserdioden, gütegeschalteten Laserdioden oder die entspre¬ chende Kontrolle von Amplitude, Frequenz oder Güte von mit Laserdioden gepumpten Festkörperlasern. Die Fertigung ist problemlos mit herkömmli¬ cher Batchtechnologie gegeben, da lediglich mehrere Wafer in bekannter Weise geätzt und strukturiert werden müssen, welche anschließend als Ganzes gegeneinander positioniert und verbunden werden. Eine Einzelju- stage oder EinzelVerbindung von Elementen entfällt hier. Such an arrangement enables the two-dimensional array formation of individual laser diodes, which can be tuned in frequency, for example, but also of laser diodes which can be quickly modulated in amplitude or frequency, Q-switched laser diodes or the corresponding control of amplitude, frequency or quality of with Pumped solid-state lasers. Manufacturing is easy with conventional batch technology, since only several wafers have to be etched and structured in a known manner, which are then positioned and connected to one another as a whole. A single stage or individual connection of elements is not required here.

Claims

Lasersystem mit mikromechanisch bewegten SpiegelPatentansprüche Laser system with micromechanically moved mirrors
1. Lasersystem mit einem oder mehreren aktiv kontrollierten Laser¬ spiegeln, die durch elektrostriktive Materialien, wie Piezokeramiken be¬ wegt werden, dadurch gekennzeichnet, daß die Laserspiegel des Lasersy¬ stems jeweils durch ein auf der Basis der Mikrosystemtechnik hergestell¬ tem und aus einem Halbleitermaterial geformten Element gebildet werden, welches mit dem Verfahren der Halbleiter-Strukturierung (Ätztechnik) zum einen als Aktuator ausgebildet und zum anderen mittels optischer Be- schichtungstechnik (dielektrische oder Metallfilm-Beschichtung) zu einem das Lasersystem in seinen Emissionseigenschaften kontrollierbaren Spie¬ gelelement geformt ist.1. Laser system with one or more actively controlled laser mirrors which are moved by electrostrictive materials such as piezoceramics, characterized in that the laser mirrors of the laser system are each manufactured by a semiconductor material based on microsystem technology and from a semiconductor material Shaped element are formed, which is formed with the method of semiconductor structuring (etching technology) on the one hand as an actuator and on the other hand is formed by means of optical coating technology (dielectric or metal film coating) to a mirror element which can control the laser system in terms of its emission properties.
2. Lasersystem nach Anspruch 1, dadurch gekennzeichnet, daß der aktiv kontrollierte Laserspiegel mit einem freischwebenden Spiegelcoa- ting versehen ist.2. Laser system according to claim 1, characterized in that the actively controlled laser mirror is provided with a free-floating mirror coating.
3. Lasersystem nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der aktiv kontrollierte Laserspiegel aus einem Verbund von Halbleiter¬ elementen und optisch beschichteten SpiegelSubstratelementen gebildet wird.3. Laser system according to claim 1 or 2, characterized in that the actively controlled laser mirror is formed from a composite of semiconductor elements and optically coated mirror substrate elements.
4. Lasersystem nach einem der Ansprüche 1 bis 3, dadurch gekenn¬ zeichnet, daß das aktiv kontrollierte Spiegelelement zur Modulation der Laser-Emissionsfrequenz mit einer longitudinal gerichteten Bewegung be¬ aufschlagt wird.4. Laser system according to one of claims 1 to 3, characterized gekenn¬ characterized in that the actively controlled mirror element for modulating the laser emission frequency with a longitudinal movement be¬ be¬.
5. Lasersystem nach einem der Ansprüche I bis 4, dadurch gekenn¬ zeichnet, daß das aktiv kontrollierte Spiegelelement zur Erzeugung von Riesenimpulsen (Q-switching) mit einer Kippbewegung beaufschlagt wird. 5. Laser system according to one of claims I to 4, characterized gekenn¬ characterized in that the actively controlled mirror element for generating giant pulses (Q-switching) is applied with a tilting movement.
6. Lasersystem nach einem der Ansprüche 1 bis 5, dadurch gekenn¬ zeichnet, daß das aktiv kontrollierte Spiegelelement relativ zum Laser¬ system mittels einer komplexen Bewegung justiert oder das Lasersystem in seiner Amplitude moduliert wird.6. Laser system according to one of claims 1 to 5, characterized gekenn¬ characterized in that the actively controlled mirror element is adjusted relative to the Laser¬ system by means of a complex movement or the amplitude of the laser system is modulated.
7. Lasersystem nach einem der Ansprüche 1 bis 6, dadurch gekenn¬ zeichnet, daß eine ein- oder zweidimensionale Anordnung von in einem Halbleitermaterial monolithisch strukturierten oder auf einem Halblei¬ termaterial hybride aufgebrachten, mit Strahlumlenkeinhelten versehene Laserdioden einer ein- oder zweidimensionalen Laserspiegelanordnung ge¬ genüber positioniert sind, so daß sich in seiner Gesamtheit eine ein- oder zweidimensionale Anordnung von Laserdioden mit zumindest einem ex¬ ternen Laserspiegel je Laserdiode ergibt.7. Laser system according to one of claims 1 to 6, characterized gekenn¬ characterized in that a one- or two-dimensional arrangement of monolithically structured in a semiconductor material or hybrid applied to a Halblei¬ term material, provided with beam deflection laser diodes of a one- or two-dimensional laser mirror arrangement are positioned opposite, so that in its entirety there is a one- or two-dimensional arrangement of laser diodes with at least one external laser mirror per laser diode.
8. Lasersystem nach einem der Ansprüche 1 bis 7, dadurch gekenn¬ zeichnet, daß die Laserspiegeleinheit (20, 160) fest mit der Einheit der Laserdioden (1, 130) verbunden ist und in Größe und Anzahl der La¬ sersysteme beliebig aufgeteilt werden kann.8. Laser system according to one of claims 1 to 7, characterized gekenn¬ characterized in that the laser mirror unit (20, 160) is fixed to the unit of the laser diodes (1, 130) and can be divided in size and number of laser systems as desired .
9. Lasersystem nach einem der Ansprüche 1 bis 8, dadurch gekenn¬ zeichnet, daß eine ein- oder zweidimensionale Anordnung von auf einem Halbleitermaterial hybride aufgebrachten Laserdioden (20, 130) oder Kop¬ peloptiken und Festkörper-Laserkristallen, welche mit Strahlumlenkein- heiten (140) versehen sind, einer ein- oder zweidimensionalen Anordnung von Laserspiegeln gegebenübergestellt ist, so daß sich in seiner Gesamt¬ heit eine ein- oder zweidimensionale Anordnung von durch Laserdioden gepumpten Festkörperlasern mit zumindest einem externen Laserspiegel je Laserdiode ergibt.9. Laser system according to one of claims 1 to 8, characterized gekenn¬ characterized in that a one or two-dimensional arrangement of hybrid applied to a semiconductor material laser diodes (20, 130) or Kop¬ optics and solid-state laser crystals, which with beam deflection units ( 140) are provided, a one- or two-dimensional arrangement of laser mirrors is provided, so that the overall result is a one- or two-dimensional arrangement of solid-state lasers pumped by laser diodes with at least one external laser mirror per laser diode.
10. Lasersystem nach einem der Ansprüche 1 bis 9, dadurch gekenn¬ zeichnet, daß das die Laserdioden tragende Halbleitersubstrat (100) mit Kühlkanälen (101) zur Temperaturkonstanthaltung der wärmeerzeugenden La¬ serdioden (130) versehen ist, oder das Substrat mit einem weiteren, mit Kühlkanälen versehenene Halbleitersubstrat verbunden ist. 10. Laser system according to one of claims 1 to 9, characterized in that the semiconductor substrate (100) carrying the laser diodes is provided with cooling channels (101) for keeping the temperature of the heat-generating laser diodes (130) constant, or the substrate with a further, semiconductor substrate provided with cooling channels is connected.
11. Mikromechanischer Spiegel für Laseranwendungen mit in abwech¬ selnder Reihenfolge aufgdampfter Schichten unterschiedlicher Brechungs¬ indizes, dadurch gekennzeichnet, daß der Spiegel aus einem Silizium¬ oder einkrlstallinen (•....bleiter-)Substrat besteht, welches mit mehrla¬ gigen dielektrischen oder metallischen Schichten versehen wird und das Substrat im aktiven Spiegelbereich ätztechnisch vollständig entfernt wird, so daß das dielektrische Schichtpaket nunmehr freischwebend als Spiegel wirkt.11. Micromechanical mirror for laser applications with layers of different refractive indices which are vapor-deposited in an alternating sequence, characterized in that the mirror consists of a silicon or single crystal ( • .... conductor) substrate which is coated with multilayer dielectric or is provided with metallic layers and the substrate in the active mirror area is completely removed by etching, so that the dielectric layer package now acts as a free-floating mirror.
12. Mikromechanischer Spiegel nach Anspruch 11, dadurch gekenn¬ zeichnet, daß der aktive Spiegelbereich in seinen Reflexionseigenschaf¬ ten variabel ausgestaltet ist.12. Micromechanical mirror according to claim 11, characterized in that the active mirror region is designed to be variable in its reflection properties.
13. M1kromechan1scher Spiegel nach Aspruch 11 oder 12, dadurch ge¬ kennzeichnet, daß der optisch aktive Spiegelbereich als Gauß'scher Spiegel ausgebildet ist.13. M1kromechan1scher mirror according to claim 11 or 12, characterized ge indicates that the optically active mirror area is designed as a Gaussian mirror.
14. Mikromechanischer Spiegel nach einem der Ansprüche 11 bis 13, dadurch gekennzeichnet, daß der optisch aktive Spiegelbereich ätztech¬ nisch an dünnen Biegestegen aus dem Halbleitersubstrat oder mit einem geeigneten Dünnfilm frei beweglich aufgehängt wird.14. Micromechanical mirror according to one of claims 11 to 13, characterized in that the optically active mirror area is etched on thin bending webs from the semiconductor substrate or with a suitable thin film so that it can move freely.
15. Mikromechanischer Spiegel nach einem der Ansprüche 11 bis 14, dadurch gekennzeichnet, daß das Halbleitersubstrat elektrisch kontak¬ tiert wird, so daß der Spiegel eine Elektrode einer Kondensatoranordnung bildet, die mit einem zweiten Halbleitersubstrat verbunden wird und eine flache Vertiefung vorgesehen ist, die den Elektrodenabstand zum bewegli¬ chen Teil und damit auch die Bewegungsfreiheit des optisch aktiven Spie¬ gelbereiches festlegt.15. Micromechanical mirror according to one of claims 11 to 14, characterized in that the semiconductor substrate is electrically contacted, so that the mirror forms an electrode of a capacitor arrangement which is connected to a second semiconductor substrate and a shallow depression is provided which Electrode distance to the movable part and thus also defines the freedom of movement of the optically active mirror area.
16. Mikromechanischer Spiegel nach Anspruch 15, dadurch gekenn¬ zeichnet, daß die beiden Halbleitersubstrate durch anodisches Bonden oder direktes Si-Si-Bonden miteinander verbunden werden. 16. Micromechanical mirror according to claim 15, characterized in that the two semiconductor substrates are connected to one another by anodic bonding or direct Si-Si bonding.
17. Mikromechanischer Spiegel nach einem der Ansprüche 11 bis 16, dadurch gekennzeichnet, daß als Verstellkräfte neben dem elektrostati¬ schen Kraftprinzip auch piezoelektrische oder magnetische Kraftprinzi¬ pien einsetzbar sind und dementsprechend der Spiegelanordnung geeignete Stellelemente zugeordnet sind.17. Micromechanical mirror according to one of claims 11 to 16, characterized in that piezoelectric or magnetic force principles can also be used as adjusting forces in addition to the electrostatic force principle and, accordingly, suitable control elements are assigned to the mirror arrangement.
18. Mikromechanischer Spiegel nach einem der Ansprüche 11 bis 17, dadurch gekennzeichnet, daß der optisch aktive Spiegelbereich durch Unterdruck oder Überdruck gezielt in seiner Wölbung variierbar ist und damit die Brennweite des Spiegels verändert werden kann. 18. Micromechanical mirror according to one of claims 11 to 17, characterized in that the optically active mirror region can be specifically varied in its curvature by negative pressure or positive pressure and thus the focal length of the mirror can be changed.
PCT/EP1993/000829 1992-04-09 1993-04-03 Laser system with mirrors moved by micro-engineering techniques WO1993021553A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP93911443A EP0635142A1 (en) 1992-04-09 1993-04-03 Laser system with mirrors moved by micro-engineering techniques
JP5517944A JPH08500468A (en) 1992-04-09 1993-04-03 Laser system with mirror for micromechanic movement
US08/318,665 US5572543A (en) 1992-04-09 1994-11-29 Laser system with a micro-mechanically moved mirror

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DEP4211898.0 1992-04-09
DE4211898A DE4211898A1 (en) 1992-04-09 1992-04-09 Micro-mechanical laser mirror - has multilayer dielectric or metallic coating on silicon@ substrate which is completely etched away in optically-active region to provide floating mirror actuated capacitively, magnetically or piezoelectrically.
DE4215797A DE4215797A1 (en) 1992-05-13 1992-05-13 Laser diode micromechanical mirror e.g. for pumping solid state laser crystal
DEP4215797.8 1992-05-13

Publications (1)

Publication Number Publication Date
WO1993021553A1 true WO1993021553A1 (en) 1993-10-28

Family

ID=25913795

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1993/000829 WO1993021553A1 (en) 1992-04-09 1993-04-03 Laser system with mirrors moved by micro-engineering techniques

Country Status (3)

Country Link
EP (1) EP0635142A1 (en)
JP (1) JPH08500468A (en)
WO (1) WO1993021553A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995013638A1 (en) * 1993-11-08 1995-05-18 International Business Machines Corporation Hybrid external coupled cavity semiconductor laser device
US5572543A (en) * 1992-04-09 1996-11-05 Deutsch Aerospace Ag Laser system with a micro-mechanically moved mirror
WO2002023251A2 (en) * 2000-09-18 2002-03-21 Duke University Scanner apparatus having optical elements coupled to mems acuators
WO2017205833A1 (en) * 2016-05-26 2017-11-30 Compound Photonics Ltd Solid-state laser system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1168243A (en) * 1997-08-19 1999-03-09 Nec Corp Optical module and optical axis adjustment method
JP4210245B2 (en) 2004-07-09 2009-01-14 セイコーエプソン株式会社 Wavelength tunable filter and detection device
JP4603489B2 (en) * 2005-01-28 2010-12-22 セイコーエプソン株式会社 Tunable filter

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1196447A (en) * 1966-10-11 1970-06-24 Hitachi Ltd Laser Device
GB2157091A (en) * 1984-03-31 1985-10-16 Deutsche Forsch Luft Raumfahrt Piezoceramic servo-drive for producing translational motion, especially for application to ring laser mirrors
EP0280299A2 (en) * 1987-02-26 1988-08-31 Matsushita Electric Industrial Co., Ltd. Reflector for excimer laser and excimer laser apparatus using the reflector
US4918704A (en) * 1989-01-10 1990-04-17 Quantel International, Inc. Q-switched solid state pulsed laser with injection seeding and a gaussian output coupling mirror
US4954789A (en) * 1989-09-28 1990-09-04 Texas Instruments Incorporated Spatial light modulator
WO1991002392A1 (en) * 1989-07-29 1991-02-21 Messerschmitt-Bölkow-Blohm Gmbh Integrated microsystem

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1196447A (en) * 1966-10-11 1970-06-24 Hitachi Ltd Laser Device
GB2157091A (en) * 1984-03-31 1985-10-16 Deutsche Forsch Luft Raumfahrt Piezoceramic servo-drive for producing translational motion, especially for application to ring laser mirrors
EP0280299A2 (en) * 1987-02-26 1988-08-31 Matsushita Electric Industrial Co., Ltd. Reflector for excimer laser and excimer laser apparatus using the reflector
US4918704A (en) * 1989-01-10 1990-04-17 Quantel International, Inc. Q-switched solid state pulsed laser with injection seeding and a gaussian output coupling mirror
WO1991002392A1 (en) * 1989-07-29 1991-02-21 Messerschmitt-Bölkow-Blohm Gmbh Integrated microsystem
US4954789A (en) * 1989-09-28 1990-09-04 Texas Instruments Incorporated Spatial light modulator

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
APPLIED PHYSICS LETTERS. Bd. 31, Nr. 8, 15. Oktober 1977, NEW YORK US Seiten 521 - 523 K.E PETERSEN 'micromechanical light modulator array fabricated on silicon' *
PATENT ABSTRACTS OF JAPAN vol. 10, no. 317 (E-449)28. Oktober 1986 *
SOVIET JOURNAL OF QUANTUM ELECTRONICS Bd. 21, Nr. 1, Januar 1991, NEW YORK US Seiten 116 - 118 V.V. APOLLONOV ET AL 'Active correction of a thermal lens in a solid state laser,' *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5572543A (en) * 1992-04-09 1996-11-05 Deutsch Aerospace Ag Laser system with a micro-mechanically moved mirror
WO1995013638A1 (en) * 1993-11-08 1995-05-18 International Business Machines Corporation Hybrid external coupled cavity semiconductor laser device
WO2002023251A2 (en) * 2000-09-18 2002-03-21 Duke University Scanner apparatus having optical elements coupled to mems acuators
WO2002023251A3 (en) * 2000-09-18 2003-02-06 Univ Duke Scanner apparatus having optical elements coupled to mems acuators
US7420724B2 (en) 2000-09-18 2008-09-02 Duke University Scanner apparatus having electromagnetic radiation devices coupled to MEMS actuators
US7706039B2 (en) 2000-09-18 2010-04-27 Duke University Scanner apparatus having electromagnetic radiation devices coupled to MEMS actuators
US8400697B2 (en) 2000-09-18 2013-03-19 Duke University Scanner apparatus having electromagnetic radiation devices coupled to MEMS actuators
WO2017205833A1 (en) * 2016-05-26 2017-11-30 Compound Photonics Ltd Solid-state laser system

Also Published As

Publication number Publication date
EP0635142A1 (en) 1995-01-25
JPH08500468A (en) 1996-01-16

Similar Documents

Publication Publication Date Title
US5572543A (en) Laser system with a micro-mechanically moved mirror
DE10228946B4 (en) Optical modulator, display, use of an optical modulator and method for producing an optical modulator
US6961501B2 (en) Configurable photonic device
DE10213579B4 (en) Deformable mirror device
DE60132679T2 (en) Device with optical cavity
US5022745A (en) Electrostatically deformable single crystal dielectrically coated mirror
DE602004000123T2 (en) Adjustable composite lens device with MEMS control
DE60301553T2 (en) OPTICAL CIRCUIT WITH OPTICAL PLANAR HOLLOW CORE LIGHT WAVEGUIDES
KR100730253B1 (en) Optical deflection element and optical switch
DE102008012825A1 (en) Micromechanical device with tilted electrodes
EP1421429B1 (en) Resonance scanner
EP3781916B1 (en) Interferometer and method for producing an interferometer
US20060171628A1 (en) Mems element and method of producing the same, and diffraction type mems element
EP2028525A1 (en) Micro mirror device
DE60110455T2 (en) OPTICAL FILTER
WO1993021553A1 (en) Laser system with mirrors moved by micro-engineering techniques
WO2010024803A1 (en) Tunable nanowire resonant cavity for optical modulation
DE4211898C2 (en)
US20060239324A1 (en) Laser device and wavelength selecting method in laser device
DE102020112806A1 (en) SEMICONDUCTOR LASER COMPONENT AND METHOD OF OPERATING AT LEAST ONE SEMICONDUCTOR LASER
US20040100678A1 (en) Method for finesse compensation in a fabry-perot device and a fabry-perot device with high finesse
DE602004010156T2 (en) ELECTRICALLY ROTATABLE MICROSCOPE OR MICROLINE
DE4215797A1 (en) Laser diode micromechanical mirror e.g. for pumping solid state laser crystal
CN117413441A (en) Super-structured optical device integrated on VCSEL
DE10318767B4 (en) Micromechanically actuatable, optoelectronic component

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 1993911443

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 08318665

Country of ref document: US

WWP Wipo information: published in national office

Ref document number: 1993911443

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1993911443

Country of ref document: EP