CN100394229C

CN100394229C - 2-dimensional photonic crystal having air bridge structure and its manufacturing method

Info

Publication number: CN100394229C
Application number: CNB2004800249432A
Authority: CN
Inventors: 初田蘭子; 野田进; 浅野卓; 田中良典; 宫井英次
Original assignee: Kyoto University; TDK Corp
Current assignee: Kyoto University; TDK Corp
Priority date: 2003-08-29
Filing date: 2004-08-27
Publication date: 2008-06-11
Anticipated expiration: 2024-08-27
Also published as: CN1846157A; JP4063740B2; JP2005077711A; CN101261341A

Abstract

A two-dimensional photonic crystal, wherein a clad layer (32) is disposed on the lower side of a slab layer (31), and areas (35) having refraction index different from that of the slab layer are cyclically disposed in the slab layer. Also, the crystal comprises a spot defect (36) formed by the missing of a part of the areas. The spot defect forms a resonator resonating light of a specified wavelength. An air bridge space (37) is formed in the specified area of the clad layer to face the spot defect. Since the slab layer is supported by the clad layer in those areas other than the area in which the air bridge space is formed, the mechanical strength of the two-dimensional photonic crystal is high. Since the air bridge space (37) is present under the spot defect (36), light can be easily entrapped in the spot defect (36) due to a difference in refraction factor between the slab layer (31) and air. Accordingly, the spot defect (36) forms the resonator having high performance.

Description

2 D photon crystal and manufacture method thereof with air bridge structure

Technical field

The present invention relates to employed 2 D photon crystal such as multiplexer-demultiplexer in the fields such as wavelength division multiplexing communications.Be particularly related to a kind of have in a part be provided with on the clad in space, be provided with the 2 D photon crystal and the manufacture method thereof of structure of the thin plate of 2 D photon crystal.In this application, this structure is called " air bridge structure ", the space is called " air bridges space ".

Background technology

(1) about photonic crystal

In recent years, gazed at as the photonic crystal of optical functional materials with periodic refractive index distribution.Photonic crystal has following feature, promptly distributes relatively by its periodic refractive index that light and electromagnetic energy form band structure, can not propagates light and electromagnetic energy area (photon band gap) thereby form.In addition, in employed in this application " light ", also comprise light electromagnetic wave in addition.

By in photonic crystal, importing suitable defective, can in photon band gap, form energy level (defect level).Thus, in wavelength (frequency) scope corresponding with energy in the photon band gap, only the light with the corresponding wavelength of energy of defect level can exist at this defective locations.Can form the guided wave path by this defective is made as wire, form optical resonator by being made as point-like.In this spot defect, the light wavelength of resonance (resonant wavelength) exists with ... its shape and refractive index.

Studying by using this resonator and guided wave path to make various optical devices.For example, by this resonator being configured near the guided wave path, form and both brought into play function as channel-splitting filter, bring into play the multiplexer-demultiplexer of function again as wave multiplexer, described channel-splitting filter is used for the light of the various wavelength that will propagate in the guided wave path, the light that wavelength is consistent with the resonant wavelength of resonator is derived to the outside from the guided wave path by resonator; The light that described wave multiplexer will have the resonator resonant wavelength imports to the guided wave path by resonator from the outside.This multiplexer-demultiplexer for example can be used to wave division multiplex mode communication in optical communication field, described wave division multiplex mode communication is the light of propagating a plurality of wavelength on an optical fiber, and the signal that mounting is distinguished on the light of different wave length.

Have one-dimensional crystal, two dimensional crystal, three-dimensional crystal in photonic crystal, wherein 2 D photon crystal has to make and is relatively easy to advantage.As an one example, in patent documentation 1, record: on the sheet material (thin plate) of high index of refraction, have the 2 D photon crystal of the periodic arrangement material lower, and make the guided wave path of this periodic arrangement defective with wire than this material refractive index; With the spot defect that this periodic arrangement is upset and guided wave path in abutting connection with and the 2 D photon crystal and the multiplexer-demultiplexer that are provided with.In addition, as mentioned above, the guided wave path that will be formed in this application in the 2 D photon crystal is called " guided wave path in the crystal ".

Patent documentation 1: the spy opens 2001-272555 communique ((0019)～(0032), Fig. 1).

Generally, for difference that can increase the rate of penetrating and the simplification that realizes making, in 2 D photon crystal, the region of low refractive index that periodically is disposed in the high index of refraction thin plate is made as air (that is emptying aperture).

In the 2 D photon crystal of patent documentation 1 record, thin plate is all contacting with air up and down.As previously mentioned, because the difference of the refractive index between thin plate and the air is bigger, thereby its most of meeting of the light of propagating in the guided wave path in crystal be closed in thin plate inside by total reflection, thereby can access higher propagation efficiency.

(2) relation of the substrate of 2 D photon crystal and resonator (spot defect)

As patent documentation 1 was disclosed, usually owing to require sheet gauge quite thin (being about 0.25 μ m in an embodiment), so the intensity of thickness direction was lower.Particularly by being provided with on thin plate in the 2 D photon crystal that a plurality of emptying apertures form, the intensity of thickness direction can further reduce.If the intensity of thickness direction is low, then can produce the problems such as going up the yield rate variation of making.

As the structure that improves 2 D photon crystal intensity, can consider to go up the 2 D photon crystal (below, be called " belt substrate photonic crystal ") of mounting crystal at substrate (thin plate).At this moment, the top and air of crystal contacts the following and substrate contacts of crystal relatively.

But, when on this belt substrate photonic crystal, spot defect being set, compare with the situation that is provided with spot defect at the 2 D photon crystal that is air up and down of thin plate (below, claim " no substrate photonic crystal "), can reduce as the characteristic of the resonator of spot defect.Fig. 1 represents for except the having or not of substrate, and the experiment value of the resonant wavelength frequency spectrum of resonator is set under the situation of identical spot defect having on identical shaped no substrate photonic crystal (a) and the belt substrate photonic crystal (b) respectively.The half width of frequency spectrum (b) is wideer than (a's).Therefore, the belt substrate photonic crystal is compared with the situation of no substrate photonic crystal, and the wavelength resolution of its resonator is low.In addition, be the Q value as the value of representing the resonator performance, in (a), be Q=3000, and medium and small at (b) to Q=250.The belt substrate photonic crystal is bigger from the energy of the light of resonator loss.

(3) relation in substrate and fine rule guided wave path

In addition, in 2 D photon crystal,, perhaps make light guided wave route guidance outside in the crystal in order to make light guided wave path in the external orientation crystal, the present inventor, on 2 D photon crystal in succession the 2 D photon crystal in the band fine rule guided wave path in fine rule guided wave path study.Fig. 2 represents the one example.Form 2 D photon crystal 10 by on thin plate 11, periodically disposing emptying aperture 12,, form guided wave path 13 in the crystal by making emptying aperture 12 default row.Fine rule guided wave path 14 is in succession in crystal on the prolongation in guided wave path.By to form this fine rule guided wave path, 2 D photon crystal and fine rule guided wave path can be formed as one with the thin plate identical materials.

The application's inventor has calculated in crystal the light frequency of guided wave and the relation (guided wave mode) of wave number in the guided wave path and fine rule guided wave path.The result learns, as shown in Figure 2, there are two kinds of guided wave modes in the situation when all faces in fine rule guided wave path all contact with air in fine rule guided wave path.That is to say, two kinds of pattern while guided waves in a guided wave path, thus form the multiplex mode that can have the light of two wave numbers for a frequency.Because the velocity of propagation difference of the light of two kinds of patterns, therefore the existence of this multiplex mode might become obstacle when optical communication.

On the other hand, when as shown in Figure 3, when on a side in fine rule guided wave path 14, cladding parts 15 being set, as shown in Figure 4, the guided wave mode in fine rule guided wave path becomes the single-mode that only has the light of a wave number for a frequency, thereby does not produce the problems referred to above, wherein, described cladding parts 15 is low by the refractive index that has than fine rule guided wave path, but the refractive index materials higher than the refractive index of air constitutes.

As mentioned above, in the 2 D photon crystal in band fine rule guided wave path, preferred 2 D photon crystal is not all the contacting with air up and down of thin plate (therefore, contacting cladding parts), and on the other hand, preferably fine rule guided wave path contacts with cladding parts.

In patent documentation 1, put down in writing the method for making no substrate photonic crystal (not establishing fine rule guided wave path).In the method, use in the below of the layer that constitutes by InP or Si (below, claim " thin plate layer ") and have by InGaAs or SiO ₂The substrate of the layer (following one-tenth clad) that constitutes.At first, by periodically form connecting the emptying aperture of clad, and form 2 D photon crystal.At this moment, form guided wave path in spot defect and the crystal by size and the configuration that emptying aperture suitably is set.Then, by importing etchant, the clad that is present under the emptying aperture is carried out etching from the emptying aperture that forms.At this moment, by to carry out etching more than the certain hour, the clad that is present between the emptying aperture is also etched, thereby is implemented in the zone that is provided with emptying aperture, i.e. all spaces (air bridges space) that forms in the bottom of 2 D photon crystal.So in the 2 D photon crystal of making, on the air bridges space, be formed with the bridge formation shape structure (air bridge structure) that builds a bridge based on the thin plate of 2 D photon crystal.

Under the situation in integrally formed 2 D photon crystal and fine rule guided wave path, when making the 2 D photon crystal in band fine rule guided wave path, on thin plate layer, form the pattern in 2 D photon crystal and fine rule guided wave path in the lump, and can make at one stroke by etching etc. naturally.; if bottom at the 2 D photon crystal in the band fine rule guided wave path that so forms; by etching the air bridges space is set; then etchant can be immersed in the clad around fine rule guided wave path; not only the bottom of 2 D photon crystal is etched, and the just following of fine rule guided wave path also can be etched.Therefore, fine rule guided wave path become not with clad in succession, propagate and become multiplex mode.And because undercapacity, the fine rule guided wave might be lost in succession.For the anti-situation of planting here, though shielding fine rule guided wave path around, be difficult to also prevent fully that etchant from immersing from the gap between fine rule guided wave path and the screen, the part of fine rule guided wave path under just still can be etched.

And, if on the prolongation in guided wave path in the crystal, fine rule guided wave path wrong from, then the guided wave efficient between guided wave path and the fine rule guided wave path can reduce in the crystal.Therefore, when making the 2 D photon crystal of band fine rule, need accomplish in the crystal guided wave path and fine rule guided wave path as far as possible from the position relation of regulation wrong from.

Like this, because cladding parts (substrate) can impact 2 D photon crystal and resonator (spot defect) provided thereon and the intensity and the characteristic in fine rule guided wave path, therefore, need study the position that cladding parts is set in the 2 D photon crystal.And, for the appropriate location in 2 D photon crystal is provided with cladding parts, need the manufacture method of research 2 D photon crystal.

First problem that the present invention will solve is, a kind of high mechanical property of 2 D photon crystal that has than in the past is provided, and the well behaved 2 D photon crystal that resonates, and a kind of best approach of making this 2 D photon crystal is provided.

Second problem that the present invention will solve is, a kind of manufacture method of the 2 D photon crystal with fine rule guided wave path is provided, the 2 D photon crystal in described band fine rule guided wave path, the thin plate of its 2 D photon crystal is all contacting with air up and down, and in the bottom with 2 D photon crystal fine rule guided wave path in succession cladding parts is set.Particularly, in the crystal that a kind of 2 D photon crystal is provided is had the position relation in guided wave path and fine rule guided wave path do not take place wrong from manufacture method.

Summary of the invention

2 D photon crystal with air bridge structure involved in the present invention is the device of inventing in order to solve above-mentioned first problem, it is characterized in that having:

A) laminal main body;

B) be arranged on clad below the described main body;

C) cycle with regulation becomes clathrate to be configured on the described main body, and a plurality of zones different with the main body refractive index;

D) with point-like the defective in described different refractivity zone is set and the spot defect that constitutes; And

E) be located at space in the specialized range of clad towards described spot defect;

Near described spot defect, also have the guided wave path, its defective by described different refractivity zone is set to wire and forms,

The part in described guided wave path is the air bridges guided wave path portion towards described space, and the width in the guided wave path of this air bridges guided wave path portion is than the width in the guided wave path of other parts size of wide regulation only.

First mode of the manufacture method of the 2 D photon crystal with air bridge structure involved in the present invention is the method for inventing in order to solve above-mentioned first problem, it is characterized in that having:

A) emptying aperture forms operation, and the etchant that is used to form the thin plate layer that connects sheet material imports and uses emptying aperture, described sheet material is stacked and form by thin plate layer and clad;

B) the air bridges space forms operation, imports etchant by importing via etchant with emptying aperture, etchant is imported with the clad around the emptying aperture carry out etching, thereby form the space on this clad;

C) 2 D photon crystal forms operation, periodically forms by only removing the emptying aperture that thin plate layer constitutes with the size of regulation, and form the spot defect of described emptying aperture towards described space on thin plate layer.

Second mode of the manufacture method of the 2 D photon crystal with air bridge structure involved in the present invention is the method for inventing in order to solve above-mentioned second problem, it is characterized in that having:

A) 2 D photon crystal forms operation, in the specialized range of the thin plate layer of and the sheet material that forms stacked by thin plate layer and clad, emptying aperture is set periodically, and in this specialized range guided wave path in the formation crystal;

B) the air bridges space forms operation, by importing etchant via described emptying aperture, the clad of described specialized range bottom is carried out etching, thereby form the space on this clad;

C) fine rule guided wave path forms operation, from the outer rim of described specialized range the outside towards this specialized range, in described crystal on the prolongation in guided wave path only with the residual thin plate layer of Rack, and by the thin plate layer around it is removed, thereby form fine rule guided wave path.

The Third Way of the manufacture method of the 2 D photon crystal with air bridge structure involved in the present invention is the method for inventing in order to solve above-mentioned second problem, it is characterized in that having:

A) emptying aperture forms operation, forms etchant importing emptying aperture on the thin plate layer by thin plate layer and the stacked sheet material that forms of clad;

C) 2 D photon crystal in band fine rule guided wave path forms operation, by on the thin plate layer in described space, emptying aperture being set periodically, and outer rim guided wave path in its inboard formation crystal from being provided with this emptying aperture zone, form 2 D photon crystal, and, by from the outer rim that is provided with this emptying aperture zone towards its outside, in described crystal on the prolongation in guided wave path only with the residual thin plate layer of width of regulation, remove its thin plate layer on every side, form fine rule guided wave path.

Description of drawings

Fig. 1 represent to be arranged in the past no substrate photonic crystal (a) and the experiment value of the resonant wavelength frequency spectrum of the spot defect on the belt substrate photonic crystal (b).

Fig. 2 is the synoptic diagram of an example of the 2 D photon crystal in expression band fine rule guided wave path.

Fig. 3 is the synoptic diagram of an example of the 2 D photon crystal in the expression band fine rule guided wave path that is provided with cladding parts.

Fig. 4 is the chart that expression is provided with the guided wave mode in guided wave path in the fine rule guided wave path of cladding parts and the crystal.

Fig. 5 is the chart of expression to the light diffusion of the Width in fine rule guided wave path.

Fig. 6 is structural perspective, vertical view and the sectional view of an embodiment of presentation surface 2 D photon crystal from the air bridges space to spot defect of the present invention that set up.

Fig. 7 is the synoptic diagram of expression as the air bridges space of the calculating object of spot defect Q value.

Fig. 8 is the result's of the expression spot defect Q value of calculating embodiment 1 a chart.

Fig. 9 is other routine vertical views of the spot defect of expression embodiment 1.

Figure 10 is the vertical view of an example in the guided wave path of expression embodiment 1.

Figure 11 is the synoptic diagram of an embodiment (embodiment 2) of the 2 D photon crystal manufacture method of expression first mode.

Figure 12 is the SEM photo with 2 D photon crystal of the air bridge structure of making in embodiment 2.

Figure 13 is the chart that expression has in embodiment 2 the partial wave frequency spectrum of the 2 D photon crystal of the air bridge structure of making and 2 D photon crystal in the past.

Figure 14 is the synoptic diagram that the guided wave path of the width in expression guided wave path when identical sees through the band territory.

Figure 15 is the synoptic diagram of the guided wave path of expression when enlarging the guided wave path of just going up in the air bridges space by the band territory.

Figure 16 be expression when the air bridges space just on guided wave path when having the narrow zone in guided wave path see through the synoptic diagram of being with the territory.

Figure 17 is the synoptic diagram that the guided wave path of expression when there is the wide zone in guided wave path in the outside in the air bridges space sees through the band territory.

Figure 18 is the stereographic map and the sectional view of an embodiment (embodiment 4) of manufacture method of the 2 D photon crystal in the related band fine rule guided wave path of the method for expression the present invention second mode.

Figure 19 is illustrated in the manufacture method of embodiment 4, and the stereographic map of the example of spot defect is set.

Figure 20 is the electron scanning micrograph by the 2 D photon crystal in the band fine rule guided wave path of embodiment 4 manufacturings.

Figure 21 is the stereographic map of an embodiment (embodiment 5) of manufacture method of 2 D photon crystal in the related band fine rule guided wave path of method of expression Third Way of the present invention.

Figure 22 is an example in expression air bridges space, promptly with the sectional view of the 2 D photon crystal in fine rule guided wave path.

Figure 23 is illustrated in the stereographic map that the example of spot defect is set among the embodiment 5.

Figure 24 is the electron scanning micrograph by the 2 D photon crystal in the band fine rule guided wave path of embodiment 5 manufacturings.

Among the figure: 10, the 91-2 D photon crystal, the 11-thin plate, 12,35,45,51,62,72,85, the 96-emptying aperture, 13,63,73,87, guided wave path in the 94-crystal, 14,65,75,88,92-fine rule guided wave path, the 15-cladding parts, 31,611,711, the 811-thin plate layer, 32,612,712, the 812-clad, 33,613, the 813-Si layer, 36,361,3621,3622,363,364,365,46,603, the 604-spot defect, 37,371,372,373,374,375,376,44,49,52,54,64,74,83,93-air bridges cavity (air bridges space), 38,47-guided wave path, 41,61, the 81-SOI substrate, 42,82, the 95-etchant imports uses emptying aperture, 43-aqueous hydrogen fluoride solution, 66,76,86, the 97-groove, 68,69,891, the 892-resist.

Embodiment

(1) in order to solve the 2 D photon crystal that first problem is invented

In 2 D photon crystal of the present invention, comparing the very thin tabular body of thickness with the size of direction in the face is that thin plate is as main body.Coating (substrate) layer is set below main body.This clad is in order to improve the intensity of 2 D photon crystal.In addition, for convenience's sake, the face that is provided with clad is designated as " following " of main body here, but 2 D photon crystal of the present invention is not limited to clad is located at downside and use, can be to using towards configuration arbitrarily.

In this main body, with the regulation cycle dispose a plurality of zones different (different refractivity zone) with this main body refractive index, form clathrate.Thus, become the 2 D photon crystal that is formed with photon band gap, described photon band gap can make by light direction in the face of main body in this cycle determined provision wavelengths band territory and can not pass through.Because by in this 2 D photon crystal, forming above-mentioned structure, make that outside main body and main body the difference because of both refractive indexes produces total reflection between (air), so, can exposure between outside main body and main body.Here, the grid in configuration different refractivity zone is triangular lattice or square lattice etc.And, the different refractivity zone also can be than in the low or high material of main body refractive index any one, but preferred cycle is punched emptying aperture and is formed on main body.By on the different refractivity zone, emptying aperture being set, can increase poor with the refractive index of main body, the different refractivity zone can be easily formed during fabrication simultaneously, and the manufacture method of aftermentioned first mode can be easily used.

Be made as point-like by defective, form spot defect this different refractivity zone.This spot defect can be by the different refractivity zone the be had size different with other different refractivities zone, or makes it default the grade and form.And, a plurality of that defective different refractivity zone can be for or adjacency are set.Under the situation of a plurality of different refractivity area defects that are provided with adjacency, these a plurality of defectives mutually combine and become a spot defect.Spot defect has the function as resonator, and the light by the determined wavelength of its shape is resonated.And, also a plurality of spot defects can be set.Form different separately shapes by the shape that makes spot defect, can in spot defect, make the photoresonance of different wave length separately.

Towards described spot defect, in the specialized range of clad, the space is set.This space also can be only forms under spot defect, can also be in wider in contrast to this scope, and promptly in departing from the scope of certain distance, foreign side forming from the outer rim of spot defect.Be provided with outside the scope in space, main body is by clad and supported.In addition, be provided with under the situation of a plurality of spot defects, also can this space be set, a space towards a plurality of spot defects can also be set by this spot defect.In this structure, spatially adopt the air bridge structure that builds a bridge based on main body.And, will adopt the space of said method setting to be called here in " air bridges space ".

Like this, by the air bridges space is set towards spot defect, based on the performance of the optical resonator of spot defect, can be than aforementioned belt substrate photonic crystal height, and be equal to aforementioned no substrate photonic crystal.It is the reasons are as follows.At first and since the position of spot defect main body all have air up and down, so, even also can increase poor with outside refractive index, make that the light sealing effect is better at the face of clad one side of main body.And, because spot defect all is up and down air, so the parameter relevant with the characteristic of spot defect is symmetrical up and down in this position.Thus, it only is the TE ripple that the light that exists in resonator becomes, thereby the light that can prevent to be present in the resonator leaks diffusing because of photon band gap direction in the face of crystal.

In addition, because 2 D photon crystal of the present invention is supported by clad, therefore can guarantee its physical strength beyond the scope that is provided with the air bridges space.Particularly forming on the different refractivity zone under the situation of emptying aperture, owing to the physical strength that emptying aperture has reduced crystal is set, therefore structure of the present invention is useful.

Below, the size in research air bridges space.Even though only form the air bridges space just down at spot defect, just can compare the performance of improving optical resonator with the situation of aforementioned belt substrate photonic crystal, but more preferably not only spot defect just down, but play away from the zone more than the one-period of different refractivity zone the air bridges space is set from the outer rim of spot defect.Like this, by in wider scope, forming the air bridges space, can access the higher optical resonator performance that is equal to described no substrate photonic crystal.On the other hand, in order to ensure the intensity of crystal, the formation scope in preferred air bridges space is below certain size.Though this scope is slightly different because of the size in the thickness of main body and different refractivity zone and material etc., but, usually preferred at least one direction in the main surface, from the outer rim of spot defect to foreign side 25 scopes below the cycle until the different refractivity zone.As long as owing in one direction this scope is made as 25 below the cycle, just can be supported in this direction, even so other directions are designed to length more than it, also can guarantee the intensity of crystal.And, though as long as the air bridges space has the very little degree of depth, just can compare the performance of improving optical resonator with the situation of described belt substrate photonic crystal, but, for the leakage of getting rid of light fully loose and up and down asymmetry the influence of clad preferably is designed to it more than twice in cycle in different refractivity zone.

By the guided wave path further is set near spot defect, 2 D photon crystal of the present invention can be used as multiplexer-demultiplexer and uses.This guided wave path is that wire forms by the default setting with the different refractivity zone.Particularly, be preferably, different refractivity zone promptly is not set and forms by making the different refractivity zone default with wire.Thus, can be used as multiplexer-demultiplexer and use, i.e. the light of partial wave resonant wavelength and be fetched into the crystal outside from the overlapping light of a plurality of wavelength of flowing through the guided wave path, perhaps the light with resonant wavelength closes ripple to the overlapping light in guided wave path from the crystal outside.

In the part in this guided wave path under the situation in air bridges space, if form guided wave path and the part beyond it with same widths on air bridges, then air bridges guided wave path portion sees through the wavelength band territory and will shift to and see through the short wavelength side in wavelength band territory than the part (" substrate guided wave path portion ") beyond it.Because what the guided wave path was all is the common part that sees through the wavelength band territory of described two parts through the wavelength band territory, so, narrower than the situation that does not have air bridges guided wave path portion.Therefore, preferably be only than the guided wave path amplitude broad prescribed level in substrate guided wave path with the width setup in the guided wave path of air bridges guided wave path portion.Thus, because of moving to long wavelength side in the wavelength band territory that sees through of air bridges guided wave path portion, so can prevent this stricturization that sees through the wavelength band territory.

But, because the restriction on 2 D photon crystal is made, therefore the guided wave path surface part of widening to the part and the guided wave path in air bridges space is inconsistent, then form the narrower zone of guided wave path width, form the zone of guided wave path width broad in substrate guided wave path portion in air bridges guided wave path portion.Owing to,, then can not widen in the wavelength band territory that sees through that the guided wave path is all then because this regional guided wave path still is above-mentioned short wavelength side through the band territory if the narrower zone of guided wave path width can be arranged in air bridges guided wave path portion.On the other hand, under the situation in the zone that forms guided wave path width broad in substrate guided wave path portion, this regional guided wave path sees through the band territory and moves to long wavelength side, makes the common wavelength band territory that sees through of short wavelength side diminish.But, if be the light that TE ripple and TM ripple mix, then in the guided wave path, can produce the leakage of TM ripple at short wavelength side, make common see through that wavelength band is overseas also can guided wave.If the zone of the guided wave path width broad of substrate guided wave path portion only is a plurality of cycles in different refractivity zone at most, then the leakage of TM ripple can be suppressed to be practical no problem degree, thereby can effectively utilize the common wavelength band territory that sees through of broad.Therefore, in the design be by from air bridges guided wave path portion to only away from the position of predetermined distance, with the width setup in guided wave path is than the width in the guided wave path of other parts size of wide regulation only, even when making like this position mistake of change guided wave path width from, can prevent that also the common wavelength band territory that sees through in guided wave path from narrowing down.

The manufacture method of (2) first modes

Below, the manufacture method of first mode of 2 D photon crystal involved in the present invention is described.This method relates to makes above-mentioned 2 D photon crystal of the present invention, the method of the 2 D photon crystal in air bridges space promptly is set towards spot defect, particularly a kind of when being manufactured on the different refractivity zone 2 D photon crystal of emptying aperture be set the best method of using.

In the method for the manner, with thin plate (main body) layer and the sheet material that coats (substrate) folded layer by layer and formation as material.On thin plate layer, form 2 D photon crystal, on clad, form the air bridges space.As this sheet material, for example thin plate layer is made of Si, and the part that the air bridges space is set in the clad is at least used by SiO ₂The substrate that constitutes.Specifically, can use on the thick film of Si and form SiO ₂Film, and then at SiO ₂Form commercially available SOI (Silicon oninsulator) substrate of Si film on the film.Use the SOI substrate, the Si film is as thin plate layer, SiO ₂Film and Si thick film are as clad, and that form the air bridges space in the clad is SiO ₂Film.

At first, on sheet material, form the emptying aperture (emptying aperture formation operation) that connects thin plate layer.Here this emptying aperture is called " etchant imports and uses emptying aperture ".This etchant imports with a part that becomes the different refractivity zone in the 2 D photon crystal of emptying aperture after finishing.But this emptying aperture forms in the operation, does not form all different refractivity zones, only forms the part of thin plate layer.This etchant imports and for example can describe to form with etching technique by making with light imprint lithography (photo lithography) or electron ray (EB) with emptying aperture.

Then, use emptying aperture, etchant is imported in the clad by the etchant importing.Thus, etchant imports from etchant and is immersed in clad with emptying aperture, and then clad is etched.Like this, etchant imports with the clad around the emptying aperture and is removed, thereby forms air bridges space (the air bridges space forms operation) in this position.Etchant can use existing etching solution or etching gas.For example work as clad by SiO ₂Under the situation about constituting, can use aqueous hydrogen fluoride solution.

After described etching finished, periodicity formed emptying aperture by only this thin plate layer being removed prescribed level on thin plate layer.Form all different refractivity zones according to this operation.Meanwhile, towards the air bridges space, on thin plate layer, form spot defect.By being provided with the emptying aperture in other different apertures of emptying aperture or making default grade of emptying aperture form spot defect.By these operations, on thin plate layer, form 2 D photon crystal (2 D photon crystal formation operation).Emptying aperture and spot defect, identical with the method for being put down in writing in the patent documentation 1, can make with light imprint lithography (photo lithography) or EB describes and formation such as etching technique.By above-mentioned operation, the bottom that can be manufactured on spot defect is formed with the 2 D photon crystal in air bridges space.

In the situation that is used for the 2 D photon crystal multiplexer-demultiplexer etc., promptly on 2 D photon crystal of the present invention, further be provided with under the situation in guided wave path in the crystal, as long as form in the operation at described 2 D photon crystal, the defective in hole is set to wire and gets final product.And under the situation in formed air bridges space, as mentioned above, preferably the width mode wideer than other parts with the guided wave path of this part (air bridges guided wave path portion) forms the guided wave path in the guided wave path surface.And, as previously mentioned, preferably from air bridges guided wave path portion to only away from the position of distance of regulation, the width in guided wave path forms than the width in the guided wave path of other parts size of wide regulation only, even make the position of changing the guided wave path width during fabrication misplace, can prevent that also the common wavelength band territory that sees through in guided wave path from narrowing down.

According to the manufacture method of first mode involved in the present invention, can use the prior art of being utilized in the semiconductor manufacturing, the easily promptly low-cost 2 D photon crystal made from air bridge structure.

The manufacture method of (3) second modes

The manufacture method of second mode is the manufacture method of 2 D photon crystal with band fine rule guided wave path of air bridge structure.In this embodiment, also the situation with first mode is identical, with thin plate (main body) layer and the sheet material (for example SOI substrate) that coats (substrate) folded layer by layer and formation as material.

At first, the specialized range intercycle of clad emptying aperture is set.Thus, because form the periodic distribution of refractive index, become 2 D photon crystal so be provided with in the scope of emptying aperture.At this moment, form guided wave path in the crystal simultaneously.Guided wave path in the crystal generally be that the wire entanglement of the periodic arrangement by emptying aperture forms, but typical method is to be set to wire by the zone that does not form emptying aperture form.In addition, with narrowed width, perhaps make it expansion on the contrary, all play a role fully as guided wave path in the crystal by the emptying aperture configuration that shifts near its both sides.And, by will disposing with wire, and imbed other different materials with the emptying aperture on every side different apertures of emptying aperture, also can form guided wave path in the crystal certainly.Emptying aperture for example is to form by employed smooth imprint lithography, the electron ray typography or dry ecthing etc. in the manufacturing of various semiconductor devices.In 2 D photon crystal, form spot defect as required.In addition, in this operation, do not form fine rule guided wave path.

Then, by emptying aperture etchant is imported clad.Etchant is immersed in clad from emptying aperture, thus the bottom of etching emptying aperture and clad on every side thereof.Thus, be provided with the scope of emptying aperture, promptly forming the air bridges space in the bottom of 2 D photon crystal.At this moment, carry out the etched time, can make the zone in air bridges space roughly consistent with the zone of 2 D photon crystal by adjusting.Here, do not need the regional in full accord of the zone in air bridges space and 2 D photon crystal, bigger a little or a little bit smaller slightly all passable than it.Etchant can use existing etching solution or etching gas.For example at clad by SiO ₂Under the situation about constituting, can use aqueous hydrogen fluoride solution.

Then, from aforesaid specialized range, promptly the outer rim of 2 D photon crystal forms fine rule guided wave path to its outside on the prolongation in guided wave path in crystal.That is, only stay the thin plate layer of fine rule guided wave path width, and remove the thin plate layer around it.Because residual in the outside in air bridges space have clad, so so its underpart, fine rule guided wave path that forms contacts with clad.Removing when forming emptying aperture of thin plate layer is identical, can make with light imprint lithography, the electron ray typography or dry ecthing etc. and carry out.Here, the fine rule guided wave path owing to forming is configured on the prolongation in guided wave path in the previous formed crystal rightly, so the coincidence function that also can use the commercially available typography (lithography) device to be had.This coincidence function is widely used in field of semiconductor manufacture, when the alignment pattern that forms with preceding working procedure further forms pattern, and can be with the position mistake of two patterns from being suppressed at below the prescribed level.

Form when removing thin plate layer in the operation in fine rule guided wave path, need not the thin plate layer beyond the part of fine rule guided wave path is removed fully, make at the both sides in fine rule guided wave path formation groove as long as remove thin plate layer.For example removing by the electron ray typography under the situation of thin plate layer, compare with removing thin plate layer on a large scale, the method for so only removing trench portions is more or less freely.

Based on following reason, the width of this groove is preferably 1 of emptying aperture configuration more than the cycle.In addition, in this application, " cycle of emptying aperture configuration " represents the distance between the most contiguous emptying aperture.

Fig. 5 is illustrated on the Width in guided wave path, the Electric Field Distribution of the light of propagating in fine rule guided wave path.Transverse axis is represented the position of fine rule guided wave path width direction, and the scope of the symbol 21 among the figure is equivalent to the zone in fine rule guided wave path.The longitudinal axis is represented the amplitude of electric field, and the big more expression electric field of the absolute value of the longitudinal axis is big more.Though electric field also exists in the outside in fine rule guided wave path 21, from the end in fine rule guided wave path to only away from the position 22 of emptying aperture configuration one-period a, electric field is roughly 0.Therefore, as long as the width of above-mentioned groove is more than the one-period of emptying aperture configuration, in the thin plate layer of the sidepiece in fine rule guided wave path, just almost there is not the leakage of light.

In 2 D photon crystal, light guided wave path in the crystal is impregnated into the scope to a certain degree of this guided wave path width direction and propagates (still, because light can not be diffused into the place than this more close outside of scope, so the light in guided wave path does not lose in the crystal).This scope of soaking into is about 5 cycles of emptying aperture configuration.If directly in succession, then owing to the light that the guided wave path is soaked in crystal is immersed in this remaining thin plate layer, so light can produce loss than the remaining thin plate layer in the more close outside of groove of both sides, fine rule guided wave path and 2 D photon crystal.Therefore, in described fine rule guided wave path formed operation, preferably from fine rule guided wave path, 5 that further the thin plate layer of the outer edge of 2 D photon crystal are removed the emptying aperture configuration more than the cycle.Thus, can prevent that the guided wave path is soaked in crystal light is immersed in the thin plate layer that remains in the groove outside and causes damage.

Manufacture method according to second mode involved in the present invention can access following effect.Among the present invention, because at the formation 2 D photon crystal and after its underpart forms the air bridges space, from outer rim formation fine rule guided wave path outside it of 2 D photon crystal, so clad can contact the bottom in fine rule guided wave path reliably.Therefore, in the fine rule guided wave path by this method manufacturing, guided wave mode is a single-mode, can not produce by the caused problem of multiplex mode.On the other hand, because the air bridges space is formed at the bottom at 2 D photon crystal, therefore by be present in its up and down air and the refringence of thin plate, can be in 2 D photon crystal light be closed in the direction vertical, thereby the loss of light suppressed for minimum with thin plate.

(4) manufacture method of Third Way

The manufacture method of Third Way is identical with the manufacture method of second mode, is the manufacture method of 2 D photon crystal with band fine rule guided wave path of air bridge structure.In the manufacture method of the manner, also be that thin plate layer and clad is stacked and the sheet material (for example SOI) that forms as material.

At first, form the emptying aperture that connects thin plate layer.Here set emptying aperture is different with the situation of second mode, is not as the emptying aperture that is used to form the different refractivity zone of 2 D photon crystal, but for etchant is imported clad setting.Here, this emptying aperture is called " etchant imports and uses emptying aperture ".Etchant imports and uses emptying aperture, as described later, preferably is arranged at the outside in the zone of the 2 D photon crystal that becomes band fine rule guided wave path after finishing.And then preferably with the both sides in guided wave path in crystal, only the mode of almost parallel ground arrangement is provided with away from the distance of regulation in the guided wave path in this crystal.But, also can as described later this etchant be imported with the part of emptying aperture as the emptying aperture that is used to form the different refractivity zone.Etchant imports and uses emptying aperture, forms by light imprint lithography (photolithography), the electron ray typography or dry ecthing etc.

Then, use emptying aperture, etchant is imported in the clad by the etchant importing.Etchant is immersed in clad from emptying aperture, and etching is carried out in the bottom of emptying aperture and clad on every side thereof.Thus, form the air bridges space within the specific limits from emptying aperture.Etchant is identical with the situation of second mode, can use existing etching solution or etching gas.

Then, at the thin plate layer towards the air bridges space, promptly the thin plate layer on the air bridges space periodically is provided with emptying aperture.Owing to formed the period profile of refractive index thus, so in being provided with the zone of emptying aperture, become 2 D photon crystal.Here, the zone that emptying aperture is set need not regional in full accord with the air bridges space, can be bigger a little or a little bit smaller slightly than it.And, be provided with and form guided wave path in the crystal when the emptying aperture in the lump.The one or both ends in guided wave path arrive the outer edge in the zone that is provided with emptying aperture in the crystal.Guided wave path in the crystal, generally the wire entanglement of the periodic arrangement by emptying aperture forms, and typical method is to be made as wire by the zone that will not form emptying aperture to form.In addition, with narrowed width, perhaps make its expansion on the contrary, can play a role fully as guided wave path in the crystal by the emptying aperture configuration that shifts near its both sides.And, by will disposing with wire, and imbed other different materials with the emptying aperture on every side different apertures of emptying aperture, also can form guided wave path in the crystal certainly.In 2 D photon crystal, form spot defect as required.For example, can perhaps make default grade of emptying aperture form spot defect by the emptying aperture of configuration with the different apertures of emptying aperture that periodically dispose.The formation of the emptying aperture in this operation imports with etchant uses emptying aperture identical, can be undertaken by light imprint lithography, the electron ray typography or dry ecthing etc.

As mentioned above, when forming 2 D photon crystal, the end in guided wave path forms fine rule guided wave path towards the outside in air bridges space in the described crystal.This fine rule guided wave path, by the thin plate layer around removing, the thin plate layer of residual its width and forming only.Because residual in the outside in air bridges space have clad, so so the fine rule guided wave path that forms has clad in its underpart.Removing when forming emptying aperture of clad is identical, can be by light imprint lithography, electron ray imprint lithography or dry ecthing etc. carries out.

Because when forming the situation in 2 D photon crystal and fine rule guided wave path respectively with different operations, in crystal in guided wave path and the fine rule guided wave path, in the mode that overlaps with the position in formed side's guided wave path in the previous operation, form the opposing party's guided wave path, so, in the operation of back, need to carry out the location between the guided wave path.Relative therewith, because in the manufacture method of this Third Way, being formed in the same operation (the formation operation of the photonic crystal in band fine rule guided wave path) of the formation of 2 D photon crystal and fine rule guided wave path carried out, therefore need not to carry out this operation that is intended to locate, not only save time and time from youngster, can also position both reliably.

Etchant imports and uses emptying aperture, preferably is located to become the outside, zone that has fine rule guided wave path 2 D photon crystal after finishing.Thus, can more at random carry out the formation that etchant imports the air bridges space of carrying out with the formation of emptying aperture with by etchant, thereby make the manufacturing process simplification.On the other hand, also etchant can be imported with emptying aperture and be located in the zone of 2 D photon crystal in band fine rule guided wave path, and this etchant is imported with emptying aperture as the part of the emptying aperture of the formed 2 D photon crystal of aftermentioned or spot defect etc.But under this situation, the 2 D photon crystal in band fine rule guided wave path forms in the operation, carry out etchant and import the location of using emptying aperture and 2 D photon crystal pattern.

And, preferred etchant import with emptying aperture for the both sides in guided wave path in crystal in this crystal the road wave path only away from a plurality of emptying apertures of predetermined distance almost parallel ground arrangement.

An etchant importing only is being set with under the situation of emptying aperture, the outer rim in air bridges space is shaped as circle.In addition, most wire etchants importings are being set with under the situation of emptying aperture, because clad is the only quilt etching respectively away from same distance from each emptying aperture, so, the outer rim in air bridges space is shaped as with etchant and imports the row parallel ribbon of using emptying aperture, and the end of its band is the circular-arc shape at center for the emptying aperture with the top.As if the outer rim that the end in guided wave path in the described crystal is disposed at these circular shapes, then there is not the air bridges space in the Width to this guided wave path from this position.Therefore, the part of 2 D photon crystal not with the air bridges space in succession.

Relative therewith, if the both sides in guided wave path in crystal, in this crystal the guided wave path only away from predetermined distance almost parallel ground arrange etchant and import and use emptying aperture, then formed air bridges space to become the shape of sidepiece coincidence of the band in its above-mentioned air bridges space.At this moment, the end in guided wave path in crystal becomes the shape that the circular shape zone in above-mentioned banded air bridges space intersects.Therefore, also there is the air bridges space in the Width of end to this guided wave path in guided wave path in the crystal, and 2 D photon crystal is all and the air bridges space in succession.Like this, even light guided wave path in the crystal is soaked into as previously mentioned, this light can not lose by clad yet.

Under the situation of Third Way, identical with the situation of second mode, preferably form in the operation in fine rule guided wave path, remove thin plate layer (not needing the thin plate layer beyond the part of fine rule guided wave path is removed fully) to need only the mode that gets final product at the both sides in fine rule guided wave path formation groove, and the width of this groove is set more than the one-period with the emptying aperture configuration.And also the situation with second embodiment is identical in described fine rule guided wave path formation operation, and preferably further the outer edge thin plate layer of 2 D photon crystal is removed the emptying aperture configuration from fine rule guided wave path 5 more than the cycle.

According to the manufacture method of Third Way involved in the present invention, can access following effect.Among the present invention, owing to after forming the air bridges space, form fine rule guided wave path in the outside in air bridges space, so, can make clad reliably in succession in the bottom in fine rule guided wave path.Therefore, in the fine rule guided wave path by this method manufacturing, guided wave mode becomes single-mode, can not produce by the caused problem of multiplex mode.And, owing to after forming the air bridges space, form 2 D photon crystal at an upper portion thereof, thus the air bridges space can be reliably in succession in the bottom of 2 D photon crystal.Therefore, the air up and down by being present in 2 D photon crystal and the refractive index of thin plate poor can be closed in light the direction vertical with the thin plate face, thereby the loss of light is suppressed to be Min..And, because the formation and being formed in the same operation of fine rule guided wave path in guided wave path are carried out in the crystal, so need not to carry out the location in guided wave path and fine rule guided wave path in the crystal, just suitably on the prolongation with fine rule guided wave path configurations guided wave path in crystal.

Embodiment 1

Fig. 6 presentation surface is provided with the structure example of the 2 D photon crystal in air bridges space to spot defect.(a) being its stereographic map, (b) being vertical view, (c) is the sectional view (left side) of the A-A ' direction shown in (b) and the sectional view (right side) of B-B ' direction.This device has: be the thin plate layer 31 of material with Si, with SiO ₂For the clad 32 of material and with Si is the Si layer 33 of material.The layer support sheet layer 31 that clad 32 and Si layer 33 overlap.

Cycle with the triangular lattice shape on thin plate layer 31 is disposed emptying aperture 35.Owing to form photon band gap thus, so can't in body layer, propagate with the light of the corresponding wavelength of energy in the photon band gap.Here, the cycle a of triangular lattice is 0.41 μ m.In addition, by making three emptying apertures 35 arranging with linearity default, three emptying apertures promptly are not set form a spot defect 36.In the clad 32, there is not SiO in the lower area setting of spot defect ₂Air bridges space 37.Because this air bridges space is to center on its empty shape zone on every side with thin plate layer 31, clad 32 and Si layer 33, so, here the air bridges space is called in " air bridges cavity ".As for the scope that this air bridges cavity 37 is set, the back will be described in detail.

In the downside and clad 32 zone in succession of thin plate layer 31, by Si (refractive index～3.5) and SiO ₂The refractive index of (refractive index～1.5) poor can be closed in light the direction perpendicular to thin plate layer 31 to a certain degree.But than the situation that body layer contacts with air, this sealing is abundant inadequately, if there is SiO in hypothesis under spot defect 36 ₂, then light can leak from spot defect 36 and loose to clad 32.And, owing to produce asymmetry up and down,, make light to leak and loose in the face of thin plate layer 31 from spot defect 36 so can produce the combination of TE ripple and TM ripple in the position of spot defect 36.Therefore, in the bottom of spot defect 36 air cavity 37 is set in the present embodiment, it is diffusing in the face of clad 32 and thin plate layer 31 to have prevented that light from leaking from spot defect 36.

For having the like this 2 D photon crystal of structure of Fig. 6, by based on time zone method of difference (Finite Difference Time Domain method; The FDTD method) calculates, try to achieve the Q value of spot defect 36.Here, for the scope that air bridges cavity 37 is set only under spot defect 36 (Fig. 7 (a)), from spot defect 36 to the outside of only departing from the grid one-period (b) and from spot defect 36 to the situation that only departs from the grid outside in two cycles (c), calculate the Q value respectively.In addition, the degree of depth in air bridges cavity 37 is made as 2a.And, in order to compare, for the situation that all whole face is formed air up and down (no substrate photonic crystal) of thin plate 31 and comprising spot defect 36 under whole of the bottom of thin plate layer 31 on the situation (belt substrate photonic crystal) of clad 32 is set, calculate the Q value.Fig. 8 represents these result of calculation.In addition, in Fig. 8, will not have the substrate photonic crystal and simply be expressed as " no substrate ", the belt substrate photonic crystal simply will be expressed as " belt substrate ".Under the situation of (b), (c), can access and do not have an equal Q value of spot defect that is provided with on the substrate photonic crystal.Therefore, air bridges cavity 37 can guarantee that promptly the scope of the intensity of thin plate layer 31 gets final product in than (b) wider scope.As mentioned above as can be known, can realize having than the more high performance spot defect resonator of the 2 D photon crystal of present embodiment.

Also there is variety of way in the spot defect that is formed at thin plate layer 31 except shown in Figure 6.Fig. 9 shows its several examples.(a) be than the big spot defect 361 that forms in the aperture of other emptying apertures by an aperture in the emptying aperture 35.This spot defect can easily be controlled resonant wavelength by changing its aperture.(b) be that two identical spot defects are set up in parallel and the spot defect that forms.These two spot defects 3621 and 3622 are provided with an air bridges cavity 372 relatively.Two spot defects 3621 and 3622 photoresonances with identical wavelength play a role as a resonator.(c) be the different a plurality of spot defects 363～365 of configuration on a photonic crystal with (d).In each spot defect 363～365, the light to different wave length resonates respectively.In (c), air bridges cavity 373～375 is set respectively by each spot defect.Relative therewith, in (d), these spot defects 363～365 whole are provided with a common air bridges cavity 376.Though this air bridges cavity 376 is bigger than air bridges cavity 373～375, because the length L of direction is shorter in the face vertical with the orientation of spot defect 363～365, so can guarantee enough intensity.

Figure 10 is illustrated in the example that the guided wave path is set in the 2 D photon crystal of the present invention.Guided wave path 38 is by making emptying aperture 35 default with wire, promptly constituting by emptying aperture 35 is not set.And, also can merely make emptying aperture 35 default, and then suitably set the width in guided wave path 38 by the arrangement of the emptying aperture 35 that staggers from the grid point of the triangular lattice that is arranged with emptying aperture 35, can adjust light wavelength band through the guided wave path.By this guided wave path is set near spot defect, can be used as multiplexer-demultiplexer uses, specifically the light to resonant wavelength carries out partial wave from the overlapping light of a plurality of wavelength of flowing through the guided wave path, and be taken out to the outside of crystal, perhaps the light with resonant wavelength closes ripple to the overlapping light in guided wave path from the crystal outside.

Embodiment 2

Below, use Figure 11 that the embodiment of manufacture method of the 2 D photon crystal of first mode is described.

Prepare SOI substrate 41, its by be the thin plate layer 31 of material with Si, with SiO ₂For the clad 32 of material and with Si is Si layer 33 this three layers of formations of material.SOI substrate 41 can use commercially available material.At first, hollowing out two etchants on thin plate layer 31 imports with emptying aperture 42 (a).Etchant imports and for example can carry out in the following manner with the formation of emptying aperture 42, promptly at the surface coated EB of thin plate layer 31 resist, and imports at etchant and to carry out with the position of emptying aperture 42 after EB describes, use etching gas (SF for example ₆) carry out dry ecthing.Then, SOI substrate 41 is immersed in the aqueous hydrogen fluoride solution 43 (b).Import the aqueous hydrogen fluoride solution that immerses with emptying aperture 42 from etchant, thin plate layer 31 and Si layer 33 are not exerted an influence, and etching clad 32 only.Thus, use emptying aperture 42 until certain distance from the etchant importing, clad 32 is etched, thereby forms air bridges space 44.Based on above-mentioned same reason, below this air bridges space is called " air bridges cavity ".Then, with the emptying aperture 45 of triangular lattice shape formation, and, form the default spot defect 46 of emptying aperture to be configured in the mode of 44 top positions, air bridges cavity as the different refractivity zone.Here, adjust the position of SOI substrate 41, making etchant import with emptying aperture 42 becomes in the regional emptying aperture of different refractivity one.The formation of this emptying aperture 45 also imports with emptying aperture 42 identically with etching, can use EB to describe or dry ecthing method carries out.

And then, when the guided wave path is set, substitute (c-1), shown in figure (c-2), need only grid point in the position in guided wave path 47, do not dig out emptying aperture 45 and get final product.

Figure 12 represents scanning electron microscope (SEM) photo by the 2 D photon crystal of second embodiment example manufacturing.(a) and (b) be the photo of observing this 2 D photon crystal from the top of thin plate layer 31.Be formed with spot defect and guided wave path in this embodiment.The air bridges cavity that under this thin plate layer 31, forms because of variable color appreciable regional 48.(c) the expression SEM photo of the section of the SOI substrate 41 of zone 48 boundary vicinity being photographed from oblique upper.Clad 32 is etched, forms air bridges cavity 49.And why clad 32 is by etchings sideling (symbol 40), is because near the top of the clad 32 of body layer, can import from etchant and be etched to far position with emptying aperture 42, and according to SiO ₂Crystalline cause.

At (a) of Figure 12 with (b), the position difference between guided wave path and the air bridges cavity.Relative with the part in guided wave path in (a) by zone 48, all outsides in guided wave path in (b) by zone 48.But the position relation for guided wave path and spot defect (a) does not have different with (b).In (b), for spot defect is disposed on the air bridges cavity, and with the guided wave path configurations beyond the air bridges cavity, the outer rim of spot defect is disposed at roughly and position in succession, zone 48.

Figure 13 represents (a) and 2 D photon crystal (b), measures from the guided wave path by the result of the partial wave frequency spectrum of the light of spot defect partial wave.The measurement result of having represented the partial wave frequency spectrum of no substrate photonic crystal and belt substrate photonic crystal in the figure in the lump.The Q value of spot defect is Q=3000 in (a), is Q=950 in (b).In (a) and (b), all obtained than belt substrate photonic crystal the higher Q value of situation, particularly in (a), can access and the identical value of Q value of not having the substrate photonic crystal.Though the Q value (b) is lower slightly than the Q value of no substrate photonic crystal, can think that this is because in (b), for the outer rim with spot defect is configured in roughly position in succession, end with zone 48, how much remaining meeting below spot defect a SiO ₂Cause.

Embodiment 3

Below, in having the 2 D photon crystal of air bridge structure, illustrate to the air bridges space just on guided wave path when the guided wave path is set see through the result that resolve in the band territory.

At first, shown in Figure 14 (a), at SiO ₂The guided wave path width of just going up zone 502 of just going up zone 501 and air bridges space 52 of substrate layer equates under the situation of (width is 1.11 times of 51 cycle of emptying aperture a), light becomes the common band territory 531 shown in Figure 14 (b) in the zone that the guided wave path in zone 501 and zone 502 sees through jointly.In addition, the longitudinal axis (b) is illustrated in cycle of multiply by emptying aperture 51 on the light frequency and divided by the normalized frequency of the light velocity, transverse axis is represented the wave number of light.And dash area represents because TE ripple and the combination of TM ripple in the guided wave path makes the interior direction of TM wave direction face leak, therefore the frequency band territory of preferably not using through the band territory as the guided wave path.

Relative therewith, shown in Figure 15 (a), when making the width in the guided wave path in zone 502 expand to 1.16 times of 51 cycle of emptying aperture a by the position of regulating emptying aperture 51, shown in Figure 15 (b), the guided wave path in zone 502 sees through the band territory and shifts to lower frequency side, compare with the situation of not expanding the guided wave path width, can enlarge common band territory 532.

Then, use and above-mentioned same analysis, research is when manufacturing has the 2 D photon crystal of air bridge structure, and the border in the zone of expansion guided wave path width is from the situation of the border dislocation in air bridges space.Because shown in Figure 16 (a), when air bridges space 54 just on when having guided wave path narrow region 551, shown in Figure 16 (b), the light in band territory 56 can not see through the guided wave paths in the zone 551, so the zone 57 that sees through that the guided wave path is all does not have the situation of dislocation narrow than above-mentioned.Relative therewith, because shown in Figure 17 (a), when having the zone 552 of guided wave path broad in the outside in air bridges space 54, shown in Figure 17 (b), direction leakage in the face of TM wave direction thin plate in the light in band territory 57, but can in the guided wave path is all, propagate.The influence of then this leakage is less if zone 552 narrows down.In the band territory beyond this, there are not zone 552 situations about exerting an influence.Therefore, even there is the wide region 552 in guided wave path in the outside in air bridges space 54, the common wavelength band territory 59 that sees through in guided wave path can not narrow down yet.

Embodiment 4

Then, use Figure 18 and Figure 19, the manufacture method of the 2 D photon crystal of second embodiment is described, promptly with an embodiment of the manufacture method of the 2 D photon crystal in fine rule guided wave path.Among Figure 18, the stereographic map of each operation is represented in the left side, and the sectional view of A-A ' or B-B ' is represented on the right side.

Prepare SOI substrate 61, its by be the thin plate layer 611 of material with Si, with SiO ₂For the clad 612 of material and with Si is Si layer 613 this three layers of formations of material.SOI substrate 61 can use commercially available material.Each layer thickness of employed SOI substrate 61 is respectively in the present embodiment, and thin plate layer 611 is 0.25 μ m, and clad 612 is 1.5 μ m, and Si layer 613 is 725 μ m.At first, at the surface coated resist 68 of thin plate layer 611, utilize electron ray in the pattern that emptying aperture periodically disposes, resist 68 to be removed (a).In the present embodiment, the radius of emptying aperture is 0.12 μ m, emptying aperture be configured to triangular lattice, its Lattice constant is 0.42 μ m.At this moment, the position in guided wave path does not form emptying aperture in becoming crystal.The width in guided wave path is 0.48 μ m in the present embodiment in the crystal.In addition, guided wave path in the crystal also can form different with other by the shape with emptying aperture, or the position of offsetting emptying aperture forms.Then, by using etching gas (SF ₆Gas) dry ecthing forms emptying aperture 62 in thin plate layer 611.At this moment, the part not etched (b) of guided wave path 63 in the crystal (and then, be this spot defect) for the situation that spot defect is set.Afterwards, remove resist 68.By carrying out the operation (2 D photon crystal formation operation) here, on thin plate layer 611, form 2 D photon crystal.But in this stage, the bottom of clad 612 and 2 D photon crystal in succession.

Then, be to soak 1 minute and 30 seconds in 5% the aqueous hydrogen fluoride solution SOI substrate 61 in concentration.The aqueous hydrogen fluoride solution that immerses from emptying aperture 62 does not exert an influence to the Si of thin plate layer 611 and Si layer 613, and only to the SiO of clad 612 ₂Carry out etching.Thus, clad 612 can be etched to certain distance from each emptying aperture 62, and etched zone is connected between emptying aperture.Like this, form air bridges cavity 64 (c) in the bottom of 2 D photon crystal.In addition, in the present embodiment, on the certain width zone of thin plate layer 611 side ends, emptying aperture is not set.Thus, in the bottom 67 of side end, clad 67 is only not etched and residual with certain width.The residual fraction of this clad 612 plays the effect of supporting 2 D photon crystal.

Then, painting erosion resistant agent 69 on thin plate layer 611, and utilize electron ray only with Rack, and the resist that forms the both sides, position in fine rule guided wave path is removed.At this moment, by using coincidence (registration: the superimposed) function of electron ray drawing apparatus, make (residual) fine rule guided wave path of formation superimposed rightly in crystal on the prolongation in guided wave path 63.The width of this groove is the one-period of emptying aperture configuration.In the present embodiment,,, on resist 69, form the groove (d) of the direction that is approximately perpendicular to fine rule guided wave path in the outer edge of 2 D photon crystal with this emptying aperture while of formation.The length of the groove of this crystal outer edge, longer than 5 cycles of emptying aperture configuration, as 6 row (5.2 cycles) of emptying aperture row, its width setup is the one-period that the emptying aperture identical with the width of the side grooves in fine rule guided wave path disposes.Then, by using SF ₆Gas carries out dry ecthing, forms two grooves 66 on thin plate layer 611.Afterwards, if remove resist 69, then residuing in two thin plate layers 611 between the groove 66 becomes fine rule guided wave path 65 (e).

By above operation, can finish the formation of the 2 D photon crystal in band fine rule guided wave path, its bottom at 2 D photon crystal has air bridges cavity 64, has clad 612 in the bottom in fine rule guided wave path 65.In guided wave path 63 in the crystal of the 2 D photon crystal of being with fine rule guided wave path at this, be formed with air bridges cavity 64 in its underpart, so can not leaking in the direction of Si layer 613, light looses.And, bottom by fine rule guided wave path 65 and clad 612 in succession, the guided wave mode in fine rule guided wave path 65 is a single-mode.And because the width of the groove 66 of both sides, fine rule guided wave path is the one-period of emptying aperture configuration, the light in fine rule guided wave path 65 does not leak the thin plate layer 611 that looses to these 65 sides, guided wave path.And then, since in the crystal outer edge in the direction that is approximately perpendicular to fine rule guided wave path 65, the light that guided wave path 65 is soaked into to this Width in the crystal forms groove 66 with six row emptying apertures row (5.2 cycles), so can not leak the thin plate layer 611 that looses to 65 sides, fine rule guided wave path.

When the situation that spot defect is set, in the described operation shown in Figure 18 (a), only otherwise forming emptying aperture at destination locations gets final product.Perhaps, the shape of this position emptying aperture can also be formed with other positions different, upsetting the position configuration emptying aperture of periodic arrangement.Figure 19 (a-1) is illustrated in the figure that position 601 does not form the example of three emptying apertures, (a-2) is the figure that expression will be formed at the example that the diameter of emptying aperture of position 602 processes greatlyyer than the diameter of other emptying apertures.By with above-mentioned operation of similarly carrying out in addition, can obtain being provided with three spot defects 603 (b-1) that emptying aperture is default, or the 2 D photon crystal in the band fine rule guided wave path of the spot defect 604 (b-2) bigger than other emptying aperture diameters.In addition, about these spot defects, in patent documentation 1 and Te Kai 2003-279764 communique by write up.

Figure 20 represents scanning electron microscope (SEM) photo by the 2 D photon crystal in the band fine rule guided wave path of present embodiment manufacturing.(a) be the photo of the section (corresponding to the A-A ' section of Figure 18) of 2 D photon crystal portion being photographed, (b) be its enlarged photograph from oblique upper.On thin plate layer 711, periodically form emptying aperture 72, and form the interior guided wave path 73 of crystal of a default row emptying aperture 72.Air bridges cavity 74 is formed at the bottom at 2 D photon crystal.In addition, why clad 712 is tilted etching, is because clad 712 tops of close thin plate layer 711 can be etched to position far away from emptying aperture 72, and according to SiO ₂Crystallinity.(c) being the figure of the section (corresponding to the section of the B-B ' of Figure 18) from oblique upper photography fine rule guided wave path portion, (d) is the figure of this section of photographing from oblique side.By forming two grooves 76, come between it, to form fine rule guided wave path 75.And shown in (c), the bottom in fine rule guided wave path 75 and clad 712 are in succession.Thus, the guided wave mode in fine rule guided wave path 75 is a single-mode.

Embodiment 5

Then, use Figure 21 and Figure 22, the manufacture method of the 2 D photon crystal of Third Way is described, promptly with an embodiment of the manufacture method of the 2 D photon crystal in fine rule guided wave path.

Identical with embodiment 4, prepare SOI substrate 81, its by be the thin plate layer 811 of material with Si, with SiO ₂For the clad 812 of material and with Si is Si layer 813 this three layers of formations of material.At first, at the surface coated resist 891 of thin plate layer 811, and utilize electron ray in etchant imports with the pattern of emptying aperture 82, resist 891 to be removed (a).This pattern is that the emptying aperture of radius 0.12 μ m is arranged two row with rectilinear form almost parallel ground.Distance between these two row is 7.2 μ m.Then, by using etching gas (SF ₆Gas) carry out dry ecthing, on thin plate layer 811, form emptying aperture 82.Afterwards, remove resist 891 (b).

Then, be to soak three minutes in 5% the aqueous hydrogen fluoride solution SOI substrate 81 in concentration.Import the aqueous hydrogen fluoride solution that immerses with emptying aperture 82 from etchant, the Si of thin plate layer 811 and Si layer 813 is not exerted an influence, and only to the SiO of clad 812 ₂Carry out etching.Thus, clad 812 imports from each etchant and is etched to certain distance with emptying aperture 82, thereby forms the air bridges cavity 83 (c) of the sidepiece coincidence shape of two bands.Figure 22 represents from the cross section A-A of SOI substrate 81 ' (shown in Fig. 6 (c)) observe the figure in this air bridges cavity.

Then, painting erosion resistant agent 892 on thin plate layer 811, and utilize electron ray, in the pattern that emptying aperture is periodically disposed resist 892 removed (d).This emptying aperture is the emptying aperture that is used to form the periodic refractive index distribution of 2 D photon crystal.In the present embodiment, the radius of emptying aperture is 0.12 μ m, emptying aperture be configured to triangular lattice, its Lattice constant is 0.42 μ m.At this moment, the position in guided wave path does not form emptying aperture in becoming crystal.In addition, also can form differently, or the location dislocation of emptying aperture be formed guided wave path in the crystal by shape with emptying aperture with the shape of other emptying apertures.And, make the position of end, guided wave path in the crystal, overlap the position 84 that intersects in the circular shape zone in air bridges cavity 83.The coincidence function that can use commercially available offset printing (lithography) device to be had is finished this position and is overlapped.The width in guided wave path is 0.48 μ m in the present embodiment in the crystal.Meanwhile, utilize electron ray only to remove (d) with the resist 892 that Rack will form the both sides, position in fine rule guided wave path.The width setup of this groove is the one-period of emptying aperture 85.In the present embodiment, when forming this groove, in the outer edge of 2 D photon crystal, the groove (d) of the direction of formation and fine rule guided wave path approximate vertical on resist 892.The length of this crystal outer edge groove is longer than 5 cycles of emptying aperture 85, is six row (5.2 cycles) of emptying aperture 85, and its width is identical with the groove width of both sides, fine rule guided wave path, i.e. the one-period of emptying aperture 85.Then, by using SF ₆Gas carries out dry ecthing, forms emptying aperture 85 and groove 86 on clad 811.Thus, guided wave path 87 and fine rule guided wave path 88 in the crystal have been formed.Afterwards, remove resist 892 (e), then finish the formation of the 2 D photon crystal in fine rule guided wave path.

In the 2 D photon crystal in the band fine rule guided wave path of so making, 84 places are connected in the position with fine rule guided wave path 88 in crystal interior guided wave path 87.Because the Width from this position 84 in the guided wave path forms air bridges cavity 83, so it all is connected 2 D photon crystal with the air bridges cavity.Therefore, even the light of propagating in the guided wave path 87 in crystal leaches into certain scope from this guided wave path and propagates, this light can not lose because of clad 812 yet.

And, because air bridges cavity 83 is formed at the bottom in guided wave path 87 in crystal, so light does not leak the direction of loosing to Si layer 813.And on clad 812, the guided wave mode in fine rule guided wave path 88 becomes single-mode to the bottom by fine rule guided wave path 88 in succession, thereby light can be in crystal carries out guided wave between guided wave path 87 and the fine rule guided wave path 88 expeditiously.Because the width of the groove 86 of 88 both sides, fine rule guided wave path is the one-period of emptying aperture 85, so the light in fine rule guided wave path 88 does not leak the thin plate layer 811 that looses to this side, guided wave path.In addition, owing to,, form groove 86 with 5 row emptying apertures 85 in the direction of light that is approximately perpendicular to fine rule guided wave path 88 in the crystal outer edge, so the light that is soaked into to its Width in guided wave path 87 in the crystal, can not leak the thin plate layer 811 that looses to 88 sides, fine rule guided wave path.

When spot defect is set,, does not form emptying aperture and get final product at destination locations as long as in the described operation shown in Figure 21 (d).Perhaps, also the shape of this position emptying aperture can be formed with other different, dispose emptying aperture upsetting on the position of periodic arrangement.Also emptying aperture can be disposed at the position that makes the periodic arrangement entanglement.Figure 23 (a) is illustrated in the figure that 80 places, position do not form the example of three emptying apertures, (b) is the figure that expression will be formed at the example that the emptying aperture diameter of position 802 processes greatlyyer than the diameter of other emptying apertures.By carry out operation in addition same as described abovely, can obtain being provided with the spot defect (situation of (a)) of default three emptying apertures, the 2 D photon crystal in the band fine rule guided wave path of perhaps big spot defect (situation of (b)) than other emptying aperture diameters.In addition, the defective that is formed at position 801 is identical with the defective that is formed at position 601 (Figure 19 (a-1)) of embodiment 4, and the defective that is formed at position 802 is identical with the defective that is formed at position 602 (Figure 19 (a-2)) of embodiment 4.

Figure 24 represents scanning electron microscope (SEM) photo by the 2 D photon crystal in the band fine rule guided wave path of present embodiment manufacturing.(a) be the photo of photographing, the part in all and fine rule guided wave path 92 of its expression 2 D photon crystal 91 from the upside of thin plate layer.The total length of the length direction of 2 D photon crystal 91 is 100 μ m.Among the figure, on the clad that is positioned at the regional bottom that to see because of variable color, be formed with air bridges cavity 93.

(b) be the photo that the boundary vicinity in guided wave path 94 in the crystal and fine rule guided wave path 93 is amplified.Etchant imports and forms two row with emptying aperture 95 in the outside of 2 D photon crystal.The emptying aperture 96 of 2 D photon crystal is arranged as the triangular lattice shape, in addition, forms the interior guided wave path 94 of crystal of a default row emptying aperture 96.Between two grooves 97, form fine rule guided wave path 92.And then the connecting portion in guided wave path 94 and fine rule guided wave path 92 also forms groove 97 on the direction that is approximately perpendicular to fine rule guided wave path in the crystal.Show enlarging near this connecting portion as (c).Guided wave path 94 and fine rule guided wave path 92 in these crystal, the outer rim in air bridges cavity 93, promptly two circular arcs 981 are connected with 982 intersection point 99 places.Therefore, also have air bridges cavity 93 from connecting portion on perpendicular to the direction in guided wave path, like this, 2 D photon crystal all is formed on the air bridges cavity 93.

Claims

1. 2 D photon crystal with air bridge structure has:

A) laminal main body; With

B) be arranged on clad below the described main body; With

C) cycle with regulation becomes clathrate to be configured on the described main body, and a plurality of zones different with the main body refractive index; With

2. the 2 D photon crystal with air bridge structure according to claim 1 is characterized in that: described different refractivity zone forms by emptying aperture is set on main body.

3. the 2 D photon crystal with air bridge structure according to claim 1 and 2 is characterized in that: a plurality of described spot defects are set.

4. the 2 D photon crystal with air bridge structure according to claim 1 and 2, it is characterized in that: described space is corresponding to the scope in the main surface, be at least one direction in main surface, extend 1～25 cycle in different refractivity zone from the outer rim of described spot defect to the foreign side of spot defect.

5. the 2 D photon crystal with air bridge structure according to claim 1 and 2 is characterized in that: the degree of depth in described space is more than the different refractivity twice of regional cycle.

6. manufacture method with 2 D photon crystal of air bridge structure has:

A) emptying aperture forms operation, and the etchant that forms the thin plate layer that connects sheet material imports uses emptying aperture, and described sheet material is stacked and form by thin plate layer and clad;

7. the manufacture method with 2 D photon crystal of air bridge structure according to claim 6, it is characterized in that: form in the operation at described 2 D photon crystal, by the line defect of described emptying aperture is set, form the guided wave path near described spot defect.

8. the manufacture method with 2 D photon crystal of air bridge structure according to claim 7, it is characterized in that: the part in described guided wave path is formed air bridges guided wave path portion towards described space, and with the width in the guided wave path of this air bridges guided wave path portion than the width in other part guided wave paths mode of wide given size only, form the guided wave path.

9. manufacture method with 2 D photon crystal of air bridge structure has:

10. the manufacture method with 2 D photon crystal of air bridge structure according to claim 9, it is characterized in that: described fine rule guided wave path forms in the operation, in thin plate layer, only with the width more than the one-period of emptying aperture configuration, remove the both sides in fine rule guided wave path and form channel form.

11. according to claim 9 or 10 described manufacture methods with 2 D photon crystal of air bridge structure, it is characterized in that: in the formation operation in described fine rule guided wave path, and then more than the cycle, remove the thin plate layer of described 2 D photon crystal outer edge from described fine rule guided wave path with 5 of emptying aperture configuration.

12. the manufacture method with 2 D photon crystal of air bridge structure has:

13. the manufacture method with 2 D photon crystal of air bridge structure according to claim 12 is characterized in that: on the thin plate layer outside the zone of the 2 D photon crystal that becomes band fine rule guided wave path, form described etchant importing emptying aperture.

14. according to claim 12 or 13 described manufacture methods with 2 D photon crystal of air bridge structure, it is characterized in that: described etchant imports uses emptying aperture, the both sides in guided wave path in described crystal, only the distance guided wave path in this crystal with regulation also is arranged abreast.

15. according to claim 12 or 13 described manufacture methods with 2 D photon crystal of air bridge structure, it is characterized in that: the 2 D photon crystal in described band fine rule guided wave path forms in the operation, in thin plate layer, only with the width more than the one-period of emptying aperture configuration, remove the both sides in fine rule guided wave path and form channel form.

16. according to claim 12 or 13 described manufacture methods with 2 D photon crystal of air bridge structure, it is characterized in that: the 2 D photon crystal in described band fine rule guided wave path forms in the operation, and then more than the cycle, remove the thin plate layer of described 2 D photon crystal outer edge from described fine rule guided wave path with 5 of emptying aperture configuration.

17. according to each described manufacture method with 2 D photon crystal of air bridge structure in the claim 9,10,12,13, it is characterized in that: guided wave path in the described crystal is the path that the zone that do not form described emptying aperture is set to wire.