CN101073210B - Optical system including FM source and optical spectrum reshaper - Google Patents
Optical system including FM source and optical spectrum reshaper Download PDFInfo
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- CN101073210B CN101073210B CN2005800127054A CN200580012705A CN101073210B CN 101073210 B CN101073210 B CN 101073210B CN 2005800127054 A CN2005800127054 A CN 2005800127054A CN 200580012705 A CN200580012705 A CN 200580012705A CN 101073210 B CN101073210 B CN 101073210B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
- H04B10/2513—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion
- H04B10/25137—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to chromatic dispersion using pulse shaping at the transmitter, e.g. pre-chirping or dispersion supported transmission [DST]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/504—Laser transmitters using direct modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/505—Laser transmitters using external modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/5161—Combination of different modulation schemes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2210/00—Indexing scheme relating to optical transmission systems
- H04B2210/516—Optical conversion of optical modulation formats, e.g., from optical ASK to optical PSK
Abstract
In one form of the present invention, there is provided a fiber optic communication system comprising: an optical signal source adapted to receive a base binary signal and produce a first signal, and an optical spectrum reshaper or amplitude modulator adapted to reshape the first signal into a second amplitude modulation and frequency modulation signal, characterized in that: the frequency characteristics of said first signal, and the optical characteristics of said optical spectrum reshaper, being such that the frequency characteristics of said second signal are configured so as to increase the tolerance of the second signal to dispersion in a transmission fiber. In another form of the present invention, there is provided an optical transmitter comprising: a frequency modulated source for generating a first frequency modulated signal, and an amplitude modulator for receiving the first frequency modulated signal and for generating a second amplitude and frequency modulated signal.
Description
Quoting of formerly patented claim of pending trial
Present patent application:
(i) to be on November 6th, 2002 proposed by people such as Daniel Mahgerefteh, title for " POWER SOURCE FOR A DISPERSION COMPENSATIONFIBER OPTIC SYSTEM ", sequence number be 10/289,944 (attorney docket TAYE-59474-00006) pending trial formerly the part of U.S. Patent application continue;
(ii) to be on Dec 3rd, 2002 proposed by people such as Daniel Mahgerefteh, title for " HIGH-SPEED TRANSMISSION SYSTEM COMPRISING ACOUPLED MULTI-CAVITY OPTICAL DISCRIMINATOR ", sequence number be 10/308,522 (attorney docket TAYE-59474-00007) pending trial formerly the part of U.S. Patent application continue;
(iii) to be on October 6th, 2003 proposed by people such as Daniel Mahgerefteh, title for " FLAT DISPERISION FREQUENCY DISCRIMINATOR (FDFD) ", sequence number be 10/680,607 (attorney docket TAYE-59474-00009) pending trial formerly the part of U.S. Patent application continue;
(iv) requiring that on February 27th, 2004 was proposed by people such as Yasuhiro Matsui, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/548,230 (attorney docket TAYE-31 PROV) for " OPTICAL SYSTEM COMPRISING AN FM SOURCE AND ASPECTRAL RESHAPING ELEMENT ", sequence number;
(v) requiring that on March 18th, 2004 was proposed by people such as Daniel Mahgerefteh, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/554,243 (attorney docket TAYE-34 PROV) for " FLAT CHIRP INDUCED BY FILTER EDGE ", sequence number;
(vi) requiring that on April 28th, 2004 was proposed by people such as Daniel Mahgerefteh, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/566,060 (attorney docket TAYE-37PROV) for " A METHOD OF TRANSMISSION USING PARTIAL FM ANDAM MODULATION ", sequence number;
(vii) requiring that on May 3rd, 2004 was proposed by people such as Daniel Mahgerefteh, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/567,737 (attorney docket TAYE-39PROV) for " ADIABATIC FREQUENCY MODULATION (AFM) ", sequence number;
(Viii) requiring that on May 10th, 2004 was proposed by people such as Daniel Mahgerefteh, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/569,769 (attorney docket TAYE-40 PROV) for " FLAT CHIRP INDUCED BY AN OPTICAL FILTEREDGE ", sequence number;
(ix) requiring that on May 10th, 2004 was proposed by people such as Daniel Mahgerefteh, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/569,768 (attorney docket TAYE-41PROV) for " METHOD OF TRANSMISSION USING PARTIAL FM ANDAM MODULATION ", sequence number;
(x) requiring that on October 25th, 2004 was proposed by people such as Kevin McCallion, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/621,755 (attorney docket TAYE-47 PROV) for " SPECTRAL RESPONSE MODIFICATION VIA SPATIALFILTERING WITH OPTICAL FIBER ", sequence number;
(xi) requiring that on November 19th, 2004 was proposed by people such as Yasuhiro Matsui, title is the pending trial interests of U.S. Provisional Patent Application formerly of 60/629,741 (attorney docket TAYE-48PROV) for " OPTICAL SYSTEM COMPRISING AN FM SOURCE AND ASPECTRAL RESHAPING ELEMENT ", sequence number;
11 patented claims that the above indicates all are combined in this by reference.
Technical field
The present invention relates generally to the signal transmission, be specifically related to the transmission of light signal and electric signal.
Background technology
The quality and performance of digital fiber transmitter is not having in the situation of serious distortion propagable distance determine by the digital signal of transmission on it.Bit error rate (BER) (BER) and a certain BER of definite acquisition at receiver place measuring-signal after passing dispersive optical fiber (are generally 10
-12, be called as susceptibility) and needed luminous power.The susceptibility of transmitter output place is called as the dispersion penalties with the difference of propagating susceptibility afterwards.This point is characterized as being usually that dispersion penalties reaches on it～distance of 1dB level.The dispersion penalties reach be called as Dispersion Limitation～the 1dB level before, the 10Gb/s optical digital transmitter (such as the light source of external modulation) of standard can transmit in the standard single-mode fiber under the 1550nm and be equivalent to～distance of 50km.Dispersion Limitation determined by the basic assumption that digital signal is converted restriction, covert position and have the bit period or 1/ (bit rate) of 100ps when namely signal does not have at its two ends.The another kind measurement of transmitter quality is the absolute susceptibility after the spread fiber.
The optical transmitting set of three types is used in the fibre system of prior art at present: (i) directly modulated laser (DML), (ii) electricity absorption modulated laser (EML) and (iii) Mach-Zehnder of external modulation (MZ).For the transmission of 10Gb/s in the standard single-mode fiber and 1550nm, suppose that usually MZ modulator and EML can have the longest accessible distance, reach 80km usually.Utilization is called as the duobinary specific coding scheme of phase-shaped, and the MZ transmitter can reach 200km.On the other hand, because directly relevant warbling of the intrinsic time of modulated laser (DML) causes the serious distortion of signal after this distance, so the direct accessible distance＜5km of modulated laser.
For instance, proposed by people such as Daniel Mahgerefteh in (i) on November 6th, 2002, title is " POWER SOURCE FOR A DISPERSIONCOMPENSATION FIBER OPTIC SYSTEM ", sequence number is 10/289, the U.S. Patent application of 944 (attorney docket TAYE-59474-00006) and (ii) proposed by people such as Daniel Mahgerefteh on October 6th, 2003, title is " FLATDISPERISION FREQUENCY DISCRIMINATOR (FDFD) ", sequence number is 10/680, the U.S. Patent application of 607 (attorney docket TAYE-59474-00009) and (iii) proposed by people such as Daniel Mahgerefteh on Dec 3rd, 2002, title is " HIGH-SPEED TRANSMISSION SYSTEM COMPRISING ACOUPLED MULTI-CAVITY OPTICAL DISCRIMINATOR ", sequence number is 10/308, the length that is used for by optical fiber is disclosed in the U.S. Patent application of 522 (attorney docket TAYE-59474-00007) apart from the various systems of light wave data transmission (under 10Gb/s greater than 80km), it is increased to the accessible distance of DML greater than 80km with 10GB/s in single-mode fiber, and above-mentioned U.S. Patent application is bonded to this by reference.Sometimes be called as the chirp management laser (CML) that the Azna LLC by the Wilmington, Massachusetts produces with the transmitter of these novel System Dependents connection
TMIn these new systems, frequency modulation (AFM) light source back is spectra shaper (OSR), and it utilizes frequency modulation to strengthen dispersion in amplitude-modulated signal and the partial-compensation Transmission Fibers.In one embodiment, the frequency modulation light source can comprise direct modulated laser (DML).Sometimes the spectra shaper (OSR) that is called as frequency discriminator can consist of by the suitable optical element with wavelength dependent transmission function.OSR is applicable to converting frequency modulation to amplitude modulation.
In the system of novelty of the present invention, the chirping characteristics of frequency modulation light source is independently revised and then also is shaped to extend CML with 10Gb/s and 1550nm on single-mode fiber by configuration OSR
TMThe accessible distance of transmitter is to more than the 250km.The system of novelty of the present invention especially combines the selection feature of the described system of following U.S. Provisional Patent Application, described U.S. Provisional Patent Application is: (i) proposed by people such as Yasuhiro Matsui on February 27th, 2004, title is that " OPTICAL SYSTEM COMPRISING AN FMSOURCE AND A SPECTRAL RESHAPING ELEMENT ", sequence number are the U.S. Provisional Patent Application of 60/548,230 (attorney docket TAYE-31 PROV); (ii) proposed by people such as Daniel Mahgerefteh on March 18th, 2004, title is that " FLATCHIRP INDUCED BY FILTER EDGE ", sequence number are the U.S. Provisional Patent Application of 60/554,243 (attorney docket TAYE-34PROV); (iii) proposed by people such as Daniel Mahgerefteh on April 28th, 2004, title is that " A METHOD OFTRANSMISSION USING PARTIAL FM AND AM MODULATION ", sequence number are the U.S. Provisional Patent Application of 60/566,060 (attorney docket TAYE-37 PROV); (iv) proposed by people such as Daniel Mahgerefteh on May 3rd, 2004, title is that " ADIABATIC FREQUENCY MODULATION (AFM) ", sequence number are the U.S. Provisional Patent Application of 60/567,737 (attorney docket TAYE-39PROV); (v) proposed by people such as Daniel Mahgerefteh on May 10th, 2004, title is that " FLAT CHIRP INDUCED BY AN OPTICAL FILTER EDGE ", sequence number are 60/569, the U.S. Provisional Patent Application of 769 (attorney docket TAYE-40PROV), above-mentioned patented claim is bonded to this by reference.
Summary of the invention
The invention provides a kind of spectra shaper (OSR), described spectra shaper and modulated light source tandem working, described modulated light source causes light transmission length considerably beyond Dispersion Limitation by the spectral characteristic of revising modulation signal.OSR can be defined as optical frequency dependent loss and frequency dependence phase place are delivered to passive optical component on the input optical signal.The present invention also provides to be increased the tolerance limit of fibre-optical dispersion and spectra shaper system and the modulated laser light source that the signal of part frequency modulation is converted to the signal of basic amplitude modulation.
Spectra shaper (OSR) can be various filters (such as coupling multi-cavity (CMC) wave filter), to strengthen the fidelity that the signal of part frequency modulation is converted to the signal of basic amplitude modulation.OSR is the partly dispersion of compensated optical fiber also.In one embodiment of the invention, the modulated laser light source can be configured to be coupled to optical filter with passing on, and its median filter is applicable to lock the wavelength of LASER Light Source and the signal that the laser signal of part frequency modulation is converted to basic amplitude modulation.
According to an aspect of the present invention, provide a kind of optical fiber telecommunications system, comprising: optical signal source, it is applicable to receive basic binary signal and produces first signal, and first signal is frequency modulation, comprises 1 and 0 with bit period; And spectra shaper, it is applicable to first signal is shaped to secondary signal, and secondary signal is amplitude modulation and frequency modulation; Wherein, the bit period of first signal and frequency displacement be used for making secondary signal by the phase differential of 1 phase place of 0 separation of odd number between pi/2 to 3 pi/2.
According to an aspect of the present invention, provide a kind of optical transmitting set, comprising: the frequency modulation light source, be used for generating the first FM signal, and amplitude modulator, the signal that is used for receiving the first FM signal and is used for generating the second amplitude modulation and frequency modulation; Wherein, the frequency displacement of the first FM signal be used for making the signal of the second amplitude modulation and frequency modulation by the phase differential of 1 phase place of 0 separation of odd number between pi/2 to 3 pi/2.
According to an aspect of the present invention, provide a kind of method for light signal being passed Transmission Fibers, method comprises: receive basic binary signal; Utilize basic binary signal operational light signal source to produce first signal, first signal is frequency modulation; Make FM signal by spectra shaper in order to first signal is shaped to secondary signal, secondary signal is amplitude modulation and frequency modulation, comprises 1 and 0 with bit period; And make secondary signal pass through Transmission Fibers; Wherein, the bit period of secondary signal and frequency displacement are used for making 1 phase differential by 0 separation of odd number between pi/2 to 3 pi/2.
According to an aspect of the present invention, provide a kind of method for the transmission baseband signal, method comprises: utilize baseband signal to produce FM signal; And provide amplitude modulator to be used for receiving FM signal and be used for generating the signal of amplitude modulation and frequency modulation; Wherein, the frequency displacement of FM signal be used for making the signal of amplitude modulation and frequency modulation by the phase differential of 1 phase place of 0 separation of odd number between pi/2 to 3 pi/2.
In a kind of form of the present invention, a kind of optical fiber telecommunications system is provided, it comprises:
Optical signal source, it is applicable to receive basic binary signal and produces first signal, and described first signal is frequency modulation; And
Spectra shaper, it is applicable to first signal is shaped to secondary signal, and described secondary signal is amplitude modulation and frequency modulation;
It is characterized in that:
The frequecy characteristic of described first signal and the optical signature of described spectra shaper increase secondary signal to the tolerance limit of dispersion in the Transmission Fibers so that the frequecy characteristic of described secondary signal is configured to.
In another kind of form of the present invention, a kind of optical transmitting set is provided, it comprises:
The frequency modulation light source is used for generating the first FM signal, and
Amplitude modulator, the signal that is used for receiving the first FM signal and is used for generating the second amplitude modulation and frequency modulation.
In another form of the present invention, a kind of method for light signal being passed Transmission Fibers is provided, the method comprises:
Receive basic binary signal;
Utilize basic binary signal operational light signal source to produce first signal, described first signal is frequency modulation;
Make FM signal by spectra shaper in order to first signal is shaped to secondary signal, described secondary signal is amplitude modulation and frequency modulation;
The frequecy characteristic of described first signal and the optical signature of described spectra shaper increase secondary signal to the tolerance limit of dispersion in the Transmission Fibers so that the frequecy characteristic of described secondary signal is configured to; And
Make secondary signal pass through Transmission Fibers.
In another kind of form of the present invention, a kind of method for the transmission baseband signal is provided, the method comprises:
Utilize baseband signal to produce FM signal; And
Provide amplitude modulator to be used for receiving FM signal and be used for generating the signal of amplitude modulation and frequency modulation.
In another form of the present invention, optical fiber telecommunications system is provided, it comprises:
Optical signal source, it is applicable to produce FM signal; And
Spectra shaper, it is applicable to FM signal is converted to the signal of basic amplitude modulation;
It is characterized in that:
The operation characteristic of optical signal source and the optical signature of spectra shaper are in conjunction with at least a portion with dispersion in the compensated optical fiber.
In another kind of form of the present invention, the method that is used for amplitude-modulated signal was passed optical fiber is provided, the method comprises:
Laser instrument is provided and the wave filter of the selectable optical signature of tool is provided;
Amplitude-modulated signal is inputted laser instrument, and operate lasers is in order to generate corresponding FM signal;
Make FM signal by wave filter in order to generate consequent signal and consequent signal is transmitted into optical fiber;
Operate lasers and selective filter are so that but consequent signal is configured at least a portion of dispersion in the compensated optical fiber.
In another form of the present invention, a kind of optical fiber telecommunications system is provided, it comprises:
Optical signal source, it is applicable to produce first signal, and described first signal is frequency modulation; And
Spectra shaper, it is applicable to convert described first signal to secondary signal, and described secondary signal is amplitude modulation and frequency modulation;
It is characterized in that:
The frequecy characteristic of described first signal and the optical signature of described spectra shaper are extended described secondary signal so that the frequecy characteristic of described secondary signal is configured to amplitude characteristic descend to surpass the distance that described secondary signal can be advanced along optical fiber before the specified rate.
In another kind of form of the present invention, a kind of optical fiber telecommunications system is provided, it comprises:
Be applicable to receive first signal and convert described first signal the module of secondary signal to, described secondary signal is amplitude modulation and frequency modulation;
It is characterized in that:
The frequecy characteristic of described secondary signal is configured in order to extend the distance that the amplitude characteristic of described secondary signal descends and can advance along optical fiber above described secondary signal before the specified rate.
In another form of the present invention, a kind of system that is applicable to first signal is converted to secondary signal is provided, described secondary signal is amplitude modulation and frequency modulation;
Its improvement comprises:
Repair the frequecy characteristic of described secondary signal in order to extend the distance that the amplitude characteristic of described secondary signal descends and can advance along optical fiber above described secondary signal before the specified rate.
In another kind of form of the present invention, a kind of optical fiber telecommunications system is provided, it comprises:
Optical signal source, it is applicable to receive baseband signal and produces first signal, and described first signal is frequency modulation; And
Spectra shaper, it is applicable to convert described first signal to secondary signal, and described secondary signal is amplitude modulation and frequency modulation;
It is characterized in that:
The frequecy characteristic of described first signal and the optical signature of described spectra shaper are extended described secondary signal so that the frequecy characteristic of described secondary signal is configured to amplitude characteristic descend to surpass the distance that described secondary signal can be advanced along optical fiber before the specified rate.
In another form of the present invention, a kind of optical fiber telecommunications system is provided, it comprises:
Optical signal source, it is applicable to produce first signal, and described first signal is frequency modulation; And
Spectra shaper, it is applicable to convert described first signal to secondary signal, and described secondary signal is amplitude modulation and frequency modulation;
It is characterized in that:
The frequency dependent loss of spectra shaper is adjusted to increase the dispersion tolerance of secondary signal.
In another kind of form of the present invention, a kind of fibre system is provided, it comprises:
Light source, it is applicable to produce frequency-modulated digital signals;
It is characterized in that:
Described digital signal has the time varying frequency modulation, its be substantially invariable at each 1 two ends and equal first frequency with and be substantially invariable and equal second frequency that the difference between wherein said first frequency and the described second frequency is between between 0.2 times and 1.0 times of bit rate frequency at each 0.
In another form of the present invention, a kind of method for generating the digital signal that dispersion allows is provided, the method comprises:
Utilize the first digital baseband signal modulation Distributed Feedback Laser generating the first optics FM signal,
A wherein said FM signal has and is the phase shift of π between by 0 separation of odd number 1, and
The amplitude of utilizing the second digital baseband signal to modulate described the first optics FM signal has the high contrast rate with generation the second light signal.
Description of drawings
According to embodiment described herein, many modifications, variation and the combination of the equipment of the optical filter of dispersion compensation and system and method are possible.When considering together with accompanying drawing, according to following detailed description, the description above of the present invention and many other features and naming a person for a particular job of following are obvious, and identical Reference numeral refers to identical part in the accompanying drawings, wherein:
Fig. 1 has illustrated with the optical digital signal of amplitude modulation and frequency modulation (being that flat-top is warbled);
Fig. 2 has illustrated instantaneous frequency and the phase place for 101 bit sequences of flat-top value of warbling of the 5GHz of 10Gb/s digital signal and 10GHz;
Having (CML output) and do not have 101 bit sequences that (standard NRZ) flat-top is warbled before Fig. 3 has illustrated and propagated and afterwards;
Fig. 4 illustrated before the OSR have Gauss pulse that adiabatic chirp distributes and consequent pulse shape and the flat-top after the OSR warbled;
Fig. 5 has illustrated that the instantaneous frequency of pulse distributes and the definition of pulse;
Fig. 6 has illustrated as the receiver susceptibility after the 200km of the function of the rise time of instantaneous frequency distribution and fall time;
Fig. 7 has illustrated that the instantaneous frequency after the OSR with two kinds of Different Slope distributes and intensity distributions;
Fig. 8 has illustrated the spectrum of adiabatic chirp signal, spectrum and the consequent shaping spectrum of OSR;
Fig. 9 has illustrated the receiver susceptibility after the 200km for the 17ps/nm/km optical fiber of various adiabatic chirp values, and signal moves with respect to the spectrum of OSR, and OSR is 3 chamber basic filters in this example;
Figure 10 has illustrated that the example of non-Gauss OSR and signal are with respect to the spectral position of OSR spectrum;
Figure 11 has illustrated the definition of OSR upgrade slope (slope of slope);
Figure 12 has illustrated that the Bessel's wave filter as OSR provides desired gradient slope;
Figure 13 illustrated passed optical fiber 200km (3400ps/nm) before and light eye afterwards and electric eye figure;
Figure 14 has illustrated that output place at laser instrument has the chirp management laser (CML of transient chirp
TM) back-to-back (back-back) eye pattern of transmitter and the 200km of optical fiber eye pattern afterwards;
Figure 15 has illustrated the gradient slope of 2 chamber etalons and the slope that records;
Figure 16 has illustrated slope and the transmission as the length bandpass filter of OSR;
Figure 17 has illustrated the example of the OSR with its dispersion profile;
Figure 18 has illustrated the relation of the fiber lengths of dispersion in susceptibility and the 17ps/nm/km optical fiber that has and do not have the OSR dispersion considered;
Figure 19 has illustrated FM source with DFB FM modulator and amplitude modulator independently;
Figure 20 has illustrated the FM source of DFB with modulation and integrated electricity absorption modulator;
Figure 21 has illustrated that the time of AM and FM signal distributes; And
Figure 22 has illustrated the optics FM/AM source with limit bandwidth OSR or wave filter.
Embodiment
In one embodiment of the invention, CML
TMGeneration has the amplitude modulation followed and the digital optical signal of frequency modulation, so that provide specific relevant between the optical phase in place.This phase place is relevant to provide the high tolerance limit of consequent light signal to dispersion in the optical fiber, has further extended CML
TMAccessible distance.
In a preferred embodiment of the invention, CML
TMFormed by direct modulation Distributed Feedback Laser and spectra shaper (OSR).Utilize electricity digital signal modulated distributed feed-back (DFB) laser instrument, wherein digital signal is with 1 and 0 bit representation.Distributed Feedback Laser is biased and is higher than its threshold value, and such as being 80mA, and it is modulated by the current-modulation of less; Consequent light signal has amplitude modulation (AM), and 1 has than 0 large amplitude.1 amplitude ratio with 0 is commonly called extinctivity (ER).Importantly, the light signal of modulation has the frequency modulation component that is called as adiabatic chirp, and it is followed amplitude modulation and almost has identical time distribution, and example wherein is illustrated in Fig. 1.The extinctivity (ER) of optics output can change in the scope of the FM efficient that depends on laser instrument, and the FM efficient of laser instrument is defined as the ratio (GHz/mA) of adiabatic chirp and modulating current.Higher modulating current increases ER and adiabatic chirp.
Directly the chirping characteristics of modulated laser is known.When utilizing electricity digital signal modulated laser instrument, its instantaneous optical frequency changes between extreme at two, and it is corresponding to 1s and 0s, and the difference of frequency change is called as adiabatic chirp.Comply with the adiabatic chirp of intensity distributions except approximate, also have the instantaneous frequency component that when the conversion of 1 to 0 and 0 to 1 position, is called as transient chirp.The value of transient chirp can be controlled in the biasing of modulating current by regulating laser relative.In one embodiment of the invention, by using high biasing and little modulation that the transient chirp component is minimized.Then signal is passed spectra shaper (OSR), as had the edge of the optical band pass filter of the acute angle gradient.OSR revises the frequency distribution of input optical signal, generates as shown in Figure 1 flat-top and square frequency distribution.As described below, in a preferred embodiment of the invention, the value that consequent flat-top is warbled is selected to so that it provides the particular phases between the position relevant.Suppose that the FM efficiency value is η
FM, desired adiabatic chirp Δ υ determines modulating current Δ i=Δ v/ η
FM, it has determined again extinctivity
I wherein
bBias current, and I
ThIt is the threshold current of laser instrument.The value that flat-top after the OSR is warbled is determined by the value of the adiabatic chirp of laser instrument output place and the slope of OSR.For 10Gb/s NRZ signal, for example, desired adiabatic chirp is～4.5GHz and for have～Distributed Feedback Laser of the FM efficient of 0.2GHz/mA ER be～1dB.Make the OSR of the average gradient of this light signal by having about 2.3dB/GHz increase this value of warbling and reach about 5GHz.The conspicuousness of this value is that phase place desired between the position as described below is relevant.
An importance of the present invention is following realization: when the frequency temporal evolution of light signal, owing to warble, depend on bit period, lifting time and chirp value, the optical phase of position changes equally.Should be noted in the discussion above that in monitoring during for sinusoidal wave optical carrier, at some time point, can be observed phase place and be the ad-hoc location on the carrier wave.Phase differential between crest and the trough is such as being π.Frequency has been described the interval between the peak value; Higher frequency means that ripple just has more crest to pass through in pack and time per unit.On mathematics, phase place is the time integral of optical frequency.When laser instrument was had the digital signal modulated of bit period T, the optical phase difference between two positions depended on that flat-top warbles, and depends on that the T.T. between the position is poor.As shown in the example below, this phase differential can be used to strengthen the propagation of signal in optical fiber.
Optical electric field is characterised in that, amplitude envelops and the time covert position and carrier frequency as follows:
E(t)＝A(t)exp(-iω
0t+iφ(t)) (1)
Wherein A (t) is amplitude envelops, ω
0The optics carrier frequency, and
Covert position when being.For example, for without warbling or the limited pulse of so-called conversion, the time covert position be zero.Instantaneous frequency by under establish an equation to define:
Be noted that negative sign in the equation 2 is based on the complex notation agreement that carrier frequency is taken as negative frequency.Therefore, the optical phase difference between two time points is provided by following formula on the light field:
Consideration is at CML
TMThe flat-top of output place 101 bit sequences with a certain value warble.With 1 frequency as reference frequency, below can obtaining at the curve map shown in two kinds of situations of the 10Gb/s digital signal (100ps duration of pulse) of flat-top value of warbling of 5GHz and 10GHz.Pulse is assumed to be to have desirable square amplitude and the flat-top of 100ps duration is warbled.Obviously, warble for the flat-top of 5GHz, have by single zero every two 1 between be the phase shift of π.
Δφ＝2πx5GHzx100ps＝π (4)
Following equation 3 and 4, is 2 π by the phase shift between two 1 of two 0 separations, and is 3 π by the phase shift between two 1 of three 0 separations, etc.Usually, warbling and the 10Gb/s signal for 5GHz, is π by two 1 phase differential of 0 separation of odd number.Warbling and the 10Gb/s square pulse for 10GHz, is synchronous by 1 of 0 separation of odd number, and namely phase differential is 2 π.
When having 101 bit sequences that the 5GHz flat-top warbles when being passed dispersive optical fiber, realize the conspicuousness of this phase shift, wherein each pulse is widened because of its limited bandwidth.Fig. 3 shows the π phase shift and causes two positions 0 center destructive interference, and therefore to keep 1 and 0 be recognizable to the decision circuit by the receiver place.Decision threshold is selected threshold voltage, surpasses threshold voltage, and all signals are counted 1; Be lower than threshold voltage, they are counted 0.Therefore, phase shift helps to distinguish 1 and 0 and pulse widening and can not reduce BER for this bit sequence.Therefore, based on the preferred embodiments of the present invention, the π phase shift that creates has increased the tolerance limit to dispersion.For the centre value of warbling, have local interference, it is enough to extend transmission range, but does not reach the distance in the said circumstances.
Light spectrum reshaping
In one embodiment of the invention, the FM modulation signal that generates by spectra shaper so that changing the instantaneous frequency of 1 and 0 two end signals distributes, in so a kind of mode in order to increase signal to the tolerance limit of dispersion.In the prior art, such as the BrP GB 2107147A that is proposed by R.E.Epworth, be filtered to produce intensity modulated from the signal in FM source, it is higher than it by the depth of modulation before the wave filter by the depth of modulation after the wave filter.In the present invention, not in amplitude modulation, to increase separately light spectrum reshaping, but utilize spectra shaper (OSR) can obtain light spectrum reshaping.In one embodiment of the invention, the instantaneous frequency of output signal is modified in its two ends after being distributed in OSR, in order to increase undistorted propagation distance.
In a preferred embodiment of the invention, semiconductor laser is directly modulated the FM modulation signal that has adiabatic chirp with generation by digital baseband signal.The output of laser instrument is then by OSR, and in this example, OSR can be the 3 chamber basic filters that use in its transmission edge.The output of warbling of frequency modulation light source (such as direct modulated laser) is adiabatic.The temporal frequency distribution that this means pulse has and the essentially identical shape of the intensity distributions of pulse.
In a preferred embodiment, proposed by people such as Daniel Mahgerefteh as the 18 days March in 2004 that is bonded to by reference this, title is that " FLAT CHIRP INDUCEDBY FILTER EDGE ", sequence number are 60/554, the U.S. Provisional Patent Application of 243 (attorney docket TAYE-34PROV) is described, and OSR converts adiabatic chirp to flat-top and warbles.
Light intensity and instantaneous frequency that Fig. 4 shows the Gauss pulse before or after the OSR distribute.Gauss pulse has the adiabatic chirp before the OSR, and namely its instantaneous frequency distributes and has the gaussian shape identical with its intensity distributions.After OSR, the distribution of amplitude and instantaneous frequency all is changed.The ratio of peak power-power (extinctivity) is increased in the background, and pulse narrows down a little in this example.Importance of the present invention is with being distributed by the flat-top instantaneous frequency that causes by OSR that empty horizontal green line represents among Fig. 4.At the spectral position of signal spectrum and the edge of OSR transmission punctual generation flat-top is warbled.The slope at adiabatic chirp and OSR transmission edge is depended in the optimum position.
The instantaneous frequency of flat-top chirped pulse distribute the slope that is characterised in that flat-top,, duration, fall time and rise time, and flat-top value of warbling shown in Figure 5.Slope can pass through two frequency values f again
2And f
1Define.In an embodiment of the present invention, the slope of the top cap portion of frequency distribution, rise time, fall time, duration were conditioned with respect to rise time of amplitude distribution, fall time, duration so that increase signal transmission range surpass Dispersion Limitation.
The importance that the instantaneous frequency of shaped pulse distributes can pass by the 10Gb/s pulse that this light spectrum reshaping is shown the simulation of the 200km bit error rate (BER) afterwards of the dispersive optical fiber with 17ps/nm/km dispersion and be familiar with.Fig. 6 shows given flat-top value of warbling that instantaneous frequency such as signal after the OSR records in distributing.In this case, can optimize rise time and fall time the BER susceptibility by changing.Similarly, given rise time and fall time for instantaneous frequency distributes, can in the scope of 3GHz to 10GHz, change the value of warbling so that obtained desired BER susceptibility after passing optical fiber.
The conclusion following according to can be calculated of this example:
(i) the best adiabatic chirp after the OSR is 5GHz, has rise time and fall time that short instantaneous frequency distributes; This has obtained minimum sensitivity after spread fiber;
(ii) any the warbling in the 3-10GHz scope can be used to respect to extending transmission without the situation of warbling.Have to regulate rise time and fall time based on the adiabatic chirp value.In the superincumbent example, less than rise time of 30ps and fall time always best; And
(iii) transmit rise time and the fall time that the slope (in dB/GHz) that distributes can reduce instantaneous frequency by increasing OSR.The slope of the flat part of frequency distribution is determined by the dispersion of OSR and further dispersion tolerance is provided.
Fig. 7 shows another embodiment, wherein is reduced by the slope (in dB/GHz) that increases OSR after OSR the rise time of instantaneous frequency distribution and fall time, is reduced to 1/2 here.In one embodiment of the invention, the output of FM signal is by being reduced by the slope (in dB/GHz) that increases OSR rise time and the fall time of OSR and frequency distribution.
Spectrum narrows down
Frequency And Amplitude Modulation has reduced the optical bandwidth of signal and has suppressed carrier frequency when having same numbers information.This effect is for the most obvious value of warbling that equals 1/2 bit rate frequency (namely the 5GHz for 10Gb/s warbles).This is corresponding to by the phase change of 0 to π between 1 of 0 separation of odd number, and namely the best between the phase place of other random bit sequences is relevant.For between the bit rate frequency 20% to 80% between the approximate extents (for the 2-8GHz of 10Gb/s bit rate) of the value of warbling, carrier wave is significantly suppressed and spectrum narrows down.For equaling 0 the value of warbling or for the warbling of the frequency that equals the bit rate frequency, carrier wave is presented and spectrum is widened again.This is to disappear because the phase place of all pulses equates for these two kinds of situations and phase place is relevant.As shown in Figure 8, the spectrum by applying FM and amplitude modulation narrows down so that the spectrum of high frequency one side narrows down.Be noted that in this example for 10Gb/s, warbling is～7.5GHz.Signal is conditioned with respect to the spectral position of OSR peak transmission, so that spectrum is positioned at the low-frequency edge of OSR.This has further reduced the spectral width of low frequency one side.Reduce spectral bandwidth and extended transmission range.
In one embodiment of the invention, the bandwidth of OSR (BW) is less than bit rate.The spectrum of digital signal is determined by the product of the Fourier transform of the spectrum of numerical information and pulse shape.Utilization provides between aforesaid by 0 separation of odd number 1 as the correct FM modulation voltage of the phase shift of π (be the warbling of 5GHz for the 10Gb/s data transfer rate) and has reduced information BW.In order to increase the tolerance limit to dispersion, still be necessary to reduce the spectrum of pulse shape.In a preferred embodiment of the invention, realize this point by limit bandwidth OSR.
Fig. 8 shows for given adiabatic chirp value, and signal can be conditioned to increase transmission range with respect to the spectral position of OSR peak transmission.The 200km susceptibility for the 10Gb/s signal afterwards that Fig. 8 shows transmitter place (back-to-back) and passed the optical fiber with 17ps/nm/km dispersion, the function that it moves for the spectrum with respect to OSR.Susceptibility is defined as reaching 10
-12The needed average light power of bit error rate (BER) (in dBm).In this example, OSR is 3 chamber etalons.Therefore, the adiabatic chirp of embodiments of the invention adjusting frequency modulation light source and consequent spectrum are with respect to the spectral position of OSR, so that obtain desired bit error rate (BER) after passing dispersive optical fiber.
Fig. 9 shows the example of the OSR that the bandpass filter by non-gaussian shape consists of.Fig. 9 shows with the transmission distribution of dB scale and derivative (derivative) or the frequency dependence slope of OSR.Fig. 9 also shows the spectral position of the input FM signal that will be shaped.The preferred embodiments of the present invention are, the optimal spectrum position of the FM signal on the OSR is so that the peak value logarithmic derivative that the 1s crest frequency distributes near the transmission of OSR.In this example, be nonlinear in dB scale upper derivate, show that OSR has the non-Gasussian light spectrum and distributes.Gauss OSR will have the linear gradient as the function of frequency.Fig. 9 also shows the position of the clock frequency component of the input FM signal that basically is reduced after OSR.This has reduced again the clock frequency component in the RF spectrum of consequent secondary signal after the OSR.In this example, the peak value slope is 2.7dB/GHz, and the three dB bandwidth of OSR is 8GHz in this case.
Concerning OSR, embodiments of the invention have also reduced the clock frequency component in the RF spectrum of consequent signal after the OSR, are 10GHz for 10Gb/s NRZ signal.
It is a kind of that best OSR shape is that transmitter has that of superperformance after its output place (back-to-back) and transmission.Determine back-to-back performance by having position distortion minimum in the eye pattern, the performance after being determined to transmit by low dispersion penalties simultaneously.Be 60/554 as the U.S. Provisional Patent Application sequence number that is bonded to by reference this, 243 (attorney docket TAYE-34PROV) and sequence number are 60/629,741 (attorney docket TAYE-48PROV) are described, and a certain filter slope value is required the adiabatic chirp input signal converted to has the signal that flat-top is warbled.It shows that also OSR converts the first derivative of the amplitude of input pulse to the blue shift transient chirp of edge.For best slope value, additional transient chirp has increased the flat-top of warbling to produce almost of edge and has warbled.
The U.S. Provisional Patent Application sequence number is that 60/554,243 (attorney docket TAYE-34PROV) and sequence number are that the actual parameter that 60/629,741 (attorney docket TAYE-48PROV) discloses OSR is its gradient slope.As shown in figure 11, as defined in the present invention, gradient slope (SoS) is the peak value logarithmic derivative (in dB/GHz) and the ratio of this peak value apart from the frequency shift (FS) (in GHz) of transmision peak of transmission.In one embodiment of the invention, the gradient slope of OSR is conditioned to optimize back-to-back transmitter BER and reduces Optical Fiber Transmission BER afterwards.For example, if gradient slope greatly about 0.38dB/GHz
2To 0.6dB/GHz
2Scope, for the 10Gb/s transmitter, good back-to-back eye pattern and the transmission after low BER can be obtained.In addition, need to be approximately linear near the slope of the OSR of transmission center.Therefore in consequent output eye pattern, introduce distortion with the deviation of linearity, and caused the bit error rate (BER) that increases.Linear gradient is corresponding to the domed shape wave filter.So, be nonconforming such as near the center, having the flat-top filter that approaches zero slope.The three dB bandwidth of the logical OSR of band is had in 65% to 90% scope of bit rate.
As shown in figure 12, two of this OSR examples are to have 2 of 6GHz or 5.5GHz bandwidth
NdRank Bessel's wave filter.2
NdThe shape of rank Bessel's wave filter it is well known to those having skill in the art that and described by following formula on mathematics:
P=2if/ Δ f wherein
3dBHere T is a transmission, and f is the optical frequency skew apart from filter center, and Δ f
3dBThe three dB bandwidth of wave filter.The amount that records is the light transmission of wave filter, and it is a squared absolute value of transmission in equation 6 | T (p) |
2And be plotted among Figure 12.Bessel's wave filter is often used as the low-pass filter of electricity, because it is so that be with the distortion in leading to minimum.In one embodiment of the invention, Bessel's wave filter is optical filter and selects it to be because it provides desired gradient slope and near the linear gradient of its peak transmission.Has 2 of 6GHz bandwidth
NdThe gradient slope of rank Bessel's wave filter is 0.46dB/GHz
2, and the 5.5GHz bandwidth 2
NdThe gradient slope of rank wave filter is 0.57dB/GHz
2These examples show that the bandwidth of wave filter can be conditioned SoS to be become desired value.
Another example that Figure 12 also shows the wave filter that can use according to the present invention is to have 4 of 7.5GHz bandwidth
ThRank Bessel's wave filter.This OSR has 0.41dB/GHz
2Gradient slope.4
ThThe field transmission of rank Bessel's wave filter is provided by following formula as the function of normalized frequency:
Figure 13 shows example back-to-back and that pass through the eye pattern that calculates after the 200km of the optical fiber with 3400ps/nm dispersion.In this example, used to have 2 of 5.5GHz bandwidth
NdRank Bessel's wave filter.The eye pattern of left column be transmitter (top) back to eye backlight (so-called O-eye) and passed 200km (3400ps/nm) eye pattern afterwards.The eye pattern of right row is to have the eye pattern that records after the photoelectric commutator of typical～8GHz bandwidth, and it is called as electric eye (E-eye).Electric eye is in output place of receiver, and it converts light signal to electric signal and provide it to decision circuit and is used for distinguishing 1 and 0.
Except adiabatic chirp, directly modulated laser also produces transient chirp, and it occurs in 1 to 0 and 0 to 1 conversion place.In the direct modulated laser of routine, transient chirp is harmful to, because it has accelerated pulse distortion and has increased the EBR after the transmission.Yet, in the present invention, having been found that when using as the FM source that wherein directly the modulated laser back is OSR, some transient chirp of laser instrument output place is desired.Figure 14 shows the analog result according to transmitter of the present invention.In this example, the adiabatic chirp of laser instrument is 4.5GHz, and OSR is near the 2 chamber basic filters that operate its transmission edge.
Figure 14 shows the 10Gb/s transmitter at the eye pattern of its output place (back-to-back), and the 200km eye pattern afterwards that passed the optical fiber with 3400ps/nm dispersion.The transient chirp of laser instrument output place before the OSR approaches zero (～0.2GHz) (left column) or be 2GHz (right row).Referring to Figure 14, obviously, the situation with 2GHz transient chirp produces the back-to-back eye pattern of less distortion.In the situation with 2GHz transient chirp, the eye pattern after the 200km optical fiber opens equally more, and has intersymbol interference (ISI) still less.Therefore, one embodiment of the present of invention are regulated the transient chirp of frequency modulation light source and the gradient slope of spectra shaper, have the desired transmitter output of minimum distortion with acquisition, and increase the inerrancy spread length of the transmitter that surpasses Dispersion Limitation.
In fact, optical filter (such as the multi-cavity etalon) may not have desired transmission shape and gradient slope.Therefore, in another embodiment of the present invention, the beam divergence and the incident angle that are mapped to the light signal of wave filter are conditioned to obtain desired SoS.Figure 15 shows the slope that records of 2 chamber etalons and as the example of the gradient slope of the function of incident angle.The peak value slope is initial to be reduced because of the angle that increases, and reaches minimum value, and then increases.Proposed by people such as Kevin McCallion as the 25 days October in 2004 that is bonded to by reference this, title is that " SPECTRAL RESPONSEMODIFICATION VIA SPATIAL FILTERING WITH OPTICALFIBER ", sequence number are 60/621, the U.S. Provisional Patent Application of 755 (attorney docket TAYE-47PROV) is described, and slope is to be caused by spatial filter than the wide-angle increase.For identical angular range, because peak increases with the angle that increases, gradient slope is from 0.75dB/GHz
2Dullness is decreased to 0.35dB/GHz
2In this example, obtain 0.45dB/GHz by incident angle being adjusted to 1.5 to 2 degree
2Optimum value.
In above-mentioned example, spectra shaper (OSR) is the multi-cavity basic filter.As shown in figure 16, in another preferred embodiment of the present invention, OSR can be the length bandpass filter.The length bandpass filter has the transmission of substantially flat to frequency range and the frequency on the edge on the side of peak transmission.In this case, the position of the first light signal will be located substantially on the Transpont slope.
The OSR dispersion
OSR also can provide some dispersion compensation and light spectrum reshaping.Figure 17 shows transmission feature and the corresponding dispersion profile thereof of wave filter.
But the fibre-optical dispersion of wave filter dispersion compensated part.For example, if laser frequency spectrum is basically overlapping with normal dispersion peak value, have negative dispersion, the transmission that then has the standard single fiber of positive dispersion is extended.If laser frequency spectrum is basically overlapping with unusual dispersion peak value, wherein dispersion is for just, then its minimizing has the transmission range of the standard fiber of positive dispersion, but the accessible distance of extending negative dispersion optical fiber (such as dispersion compensating fiber (DCF)).Figure 18 shows the susceptibility as the function of fiber distance for the situation of the OSR that has and do not have dispersion.Laser spectrum is basically overlapping with the negative dispersion peak value of OSR.As shown in figure 18, negative distance expression has the optical fiber of the negative dispersion of this length.So, represent such as ,-100km to have-the 100km dispersion compensating fiber of 17ps/nm/km dispersion.
The FM source
The present invention has instructed the several different methods that is used for generating the FM signal that dispersion with high extinctivity (ER) allows.In a preferred embodiment of the invention, generate the FM signal with two steps.
At first, select basic digital signal modulating the Distributed Feedback Laser of direct modulation, in order to generate the FM signal with adiabatic chirp, so that be the odd-multiple of π by the phase differential between two 1 of 0 separation of odd number.As an example, for the 10Gb/s NRZ signal that the instantaneous frequency with 100ps pulse and squarish distributes, this is 5GHz.
Secondly, as shown in figure 19, consequent light signal is sent out and passed the second amplitude modulator, such as LiNbO
3Modulator or electricity absorption modulator.Amplitude modulator is modulated by the second digital baseband signal, and the described second digital baseband signal is the duplicate of the first digital baseband signal.The transfer function that depends on modulator, the baseband signal that offers modulator can be converted with respect to modulated laser.That be all there be to it, such as, if higher signal has increased the loss of modulator.Therefore, high signal generation is supplied to modulator from light signal and the corresponding low signal of the more high-amplitude of laser instrument.The AM modulator can be multiple optics amplitude modulator, such as LiNbO
3Modulator or electricity absorption modulator.As shown in figure 20, DFB and EA can be integrated on the same chip.
In a preferred embodiment of the invention, the first and second baseband signals that offer laser instrument and modulator can be applicable to respectively generate FM and AM signal.Demonstrate such as Figure 21, it is different that these FM distribute in the time with the AM signal, because may have phase differential between two digital baseband signals.In addition, the rise time of the rise time of the instantaneous frequency of first signal and fall time and consequent secondary signal with may be fall time different after the AM modulator.In addition, the duration of FM and AM distribution of pulses may be different.Described as top regulation and example, in a preferred embodiment of the invention, phase delay between duration, rise time and fall time, adiabatic chirp, the amplitude modulation degree of depth and two the digital baseband signals is changed, in order to increase signal transmission to the dispersion tolerance of fibre-optical dispersion.These parameters for frequency and amplitude distribution are defined in Figure 21.
In another embodiment of the present invention, and as shown in figure 22, may have limit bandwidth wave filter or the OSR that is placed on after the above-mentioned FM/AM source.OSR or wave filter be selected to reduce such as for 10Gb/s NRZ signal under bit rate frequency 10GHz or be higher than optical frequency component under the 10GHz.
Parameter area
In various embodiment of the present invention, for the transmission of the longer distance of signal, the performance need after the spectra shaper is optimised, causes following preferred feature:
(i) AM ER＜3dB (be laser instrument intensity output extinctivity preferably less than 3dB so that make the transient chirp minimum);
(ii) scope of adiabatic chirp is at 2.5-7.5GHz (the i.e. adiabatic chirp Δ f=f of the output of laser instrument for best transmission
1-f
0≈ 2.5-7.5); And
(iii) scope of spectra shaper bandwidth is 5-10GHz (being that OSR has the effect maximization so that spectrum narrows down of the filter bandwidht of 5-10GHz).
Revise
Will appreciate that because present disclosure, the other embodiment of the present invention will be readily apparent to persons skilled in the art.Will be understood that the present invention is not subject to disclosed herein and/or the shown ad hoc structure of accompanying drawing, and comprise any modification or the equivalent that belongs to the scope of the invention.
Claims (71)
1. optical fiber telecommunications system comprises:
Optical signal source, it is applicable to receive basic binary signal and produces first signal, and described first signal is frequency modulation, comprises 1 and 0 with bit period; And
Spectra shaper, it is applicable to described first signal is shaped to secondary signal, and described secondary signal is amplitude modulation and frequency modulation;
Wherein, to be used for making in described secondary signal be π by 1 phase differential of 0 separation of odd number for the described bit period of described first signal and frequency displacement.
2. optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal be adjusted to so that the frequency displacement of described secondary signal equal described basic digital signal the bit rate frequency 1/2.
3. optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal comprises the adiabatic chirp component.
4. optical fiber telecommunications system as claimed in claim 3, the frequency displacement of wherein said first signal also comprises the transient chirp component.
5. optical fiber telecommunications system as claimed in claim 4, the frequency displacement of the transient chirp component of wherein said first signal between the bit rate frequency of described basic digital signal 0% to 30% between.
6. optical fiber telecommunications system as claimed in claim 4, the bit rate of wherein said basic digital signal is about 10Gb/s, and the frequency displacement of the transient chirp component of described first signal is 0 to 3GHz.
7. optical fiber telecommunications system as claimed in claim 1, the frequency distribution of wherein said secondary signal is flat-top.
8. optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal be adjusted to so that the frequency displacement of described secondary signal between the bit rate frequency of described basic digital signal 25% to 75% between.
9. it is π that optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal are used for making by 1 phase differential of 0 separation of odd number.
10. optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal are adjusted to so that the frequency displacement of described secondary signal equals 1/2 odd-multiple of described bit rate frequency.
11. it is the odd-multiple of π that optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal are used for making by the phase differential of 1 phase place of 0 separation of odd number.
12. optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal is used for making the frequency displacement Δ f of described secondary signal and 0 duration T of described secondary signal
0The product odd-multiple that equals 1/2.
13. optical fiber telecommunications system as claimed in claim 1, the extinctivity of wherein said secondary signal is more than or equal to 10dB.
14. optical fiber telecommunications system as claimed in claim 1, the extinctivity of wherein said secondary signal is between between the 10dB to 13dB.
15. being used for making in described secondary signal, optical fiber telecommunications system as claimed in claim 1, the frequency displacement of wherein said first signal and the dutycycle of described secondary signal equaled π by the phase differential between 1 of 0 separation of odd number.
16. optical fiber telecommunications system as claimed in claim 15, the frequency distribution of wherein said secondary signal is flat-top.
17. optical fiber telecommunications system as claimed in claim 15, the frequency distribution of wherein said first signal are not flat-tops.
18. optical fiber telecommunications system as claimed in claim 1, the rise time of the frequency distribution of wherein said secondary signal and fall time are faster than rise time and the fall time of the amplitude distribution of described secondary signal.
19. optical fiber telecommunications system as claimed in claim 1, the rise time of the frequency distribution of wherein said secondary signal and fall time are faster than rise time and the fall time of the frequency distribution of described first signal.
20. optical fiber telecommunications system as claimed in claim 1, the rise time of the frequency distribution of wherein said secondary signal is faster than the rise time of the amplitude distribution of described secondary signal.
21. optical fiber telecommunications system as claimed in claim 1, the fall time of the frequency distribution of wherein said secondary signal is faster than the fall time of the amplitude distribution of described secondary signal.
22. optical fiber telecommunications system as claimed in claim 1, the rise time of the frequency distribution of wherein said secondary signal is faster than the rise time of the frequency distribution of described first signal.
23. optical fiber telecommunications system as claimed in claim 1, the fall time of the frequency distribution of wherein said secondary signal is faster than the fall time of the frequency distribution of described first signal.
24. optical fiber telecommunications system as claimed in claim 1, the duration of the flat part of wherein said frequency distribution is enough wide, to comprise the amplitude distribution of described secondary signal.
25. optical fiber telecommunications system as claimed in claim 1, the duration of the flat part of wherein said frequency distribution only comprises the center section of the amplitude distribution of described secondary signal.
26. optical fiber telecommunications system as claimed in claim 1,1 center section of wherein said secondary signal has the frequency different from the alar part of identical bits.
27. optical fiber telecommunications system as claimed in claim 1, the center section of the amplitude distribution of wherein said secondary signal have the frequency different from the alar part on any side of center section.
28. optical fiber telecommunications system as claimed in claim 1,1 digit pulse of wherein said secondary signal has amplitude distribution and frequency distribution, wherein said frequency distribution is flat-top, and the alar part of wherein said amplitude distribution is positioned at the outside of the flat part of described frequency distribution.
29. optical fiber telecommunications system as claimed in claim 1, the amplitude distribution of wherein said secondary signal is different from its frequency distribution.
30. optical fiber telecommunications system as claimed in claim 1, the duration of the flat part of the frequency distribution of wherein said secondary signal comprises the middle body of the amplitude distribution of described secondary signal.
31. optical fiber telecommunications system as claimed in claim 30, the amplitude distribution of wherein said secondary signal comprise the alar part with frequency different from the middle body of the amplitude distribution of described secondary signal.
32. optical fiber telecommunications system as claimed in claim 1, the spectral position of wherein said first signal are positioned at the transmission edge of described spectra shaper.
33. optical fiber telecommunications system as claimed in claim 32, the spectral position of wherein said first signal is near the peak value logarithmic derivative of the transmission distribution of described spectra shaper.
Passed before the dispersive optical fiber and the bit error rate (BER) of described secondary signal afterwards 34. optical fiber telecommunications system as claimed in claim 1, the gradient slope of wherein said spectra shaper are used for optimizing simultaneously.
35. optical fiber telecommunications system as claimed in claim 34, the gradient slope of wherein said spectra shaper is between 0.38dB/GHz
2And 0.6dB/GHz
2Between.
36. optical fiber telecommunications system as claimed in claim 1, the three dB bandwidth of wherein said spectra shaper between the bit rate of described first signal 65% and 90% between.
37. being the field transmission of second order bessel filter, optical fiber telecommunications system as claimed in claim 1, the field transmission distribution of wherein said spectra shaper distribute.
38. optical fiber telecommunications system as claimed in claim 1 is linear near the log slope that the transmission of the described spectra shaper of its transmision peak distributes wherein.
39. it is the field transmission distribution of quadravalence Bessel wave filter that optical fiber telecommunications system as claimed in claim 1, the transmission of wherein said spectra shaper distribute.
40. optical fiber telecommunications system as claimed in claim 1, wherein said optical signal source is semiconductor laser.
41. optical fiber telecommunications system as claimed in claim 40, the biasing of wherein said laser instrument and the amplitude of described basic binary signal are adjusted to improve simultaneously and passed dispersive optical fiber before and the bit error rate (BER) of described secondary signal afterwards.
42. optical fiber telecommunications system as claimed in claim 40, the biasing of wherein said laser instrument and the amplitude of described basic binary signal are adjusted to improve the bit error rate (BER) that passed dispersive optical fiber described secondary signal afterwards.
43. optical fiber telecommunications system as claimed in claim 1 wherein is mapped to the beam divergence of described the first light signal of described spectra shaper and at least one in the incident angle and is adjusted to obtain desired secondary signal.
44. optical fiber telecommunications system as claimed in claim 43, wherein incident angle is between 1.5 and 2 degree.
45. optical fiber telecommunications system as claimed in claim 1, wherein said spectra shaper are the multi-cavity basic filters.
46. optical fiber telecommunications system as claimed in claim 1, wherein said spectra shaper are the length bandpass filters.
47. optical fiber telecommunications system as claimed in claim 1, the rise time of the frequency distribution of wherein said secondary signal and fall time are conditioned by the slope (dB/GHz) that the transmission of regulating described spectra shaper distributes.
48. optical fiber telecommunications system as claimed in claim 1, wherein,
Described first signal has the time varying frequency modulation, its each HFS be constant and equal first frequency with and be constant and equal second frequency that the difference between wherein said first frequency and the described second frequency is between between 0.2 times and 1.0 times of bit rate frequency in each low frequency part.
49. an optical transmitting set comprises:
The frequency modulation light source is used for generating the first FM signal, and
Amplitude modulator, the signal that is used for receiving described the first FM signal and is used for generating the second amplitude modulation and frequency modulation;
Wherein, to be used for making at the signal of described the second amplitude modulation and frequency modulation be π by 1 phase differential of 0 separation of odd number in the frequency displacement of described the first FM signal.
50. optical transmitting set as claimed in claim 49 wherein utilizes the first digital signal to modulate described frequency modulation light source and utilizes the second digital signal to modulate described amplitude modulator.
51. optical transmitting set as claimed in claim 50, the identical numerical data of wherein said the first and second digital signal representations.
52. optical transmitting set as claimed in claim 51, wherein said the first and second digital signals are logical inversion each other.
53. optical transmitting set as claimed in claim 51, wherein said the first light source is semiconductor laser.
54. optical transmitting set as claimed in claim 53, wherein said the first light source is distributed feedback laser.
55. optical transmitting set as claimed in claim 51, wherein said amplitude modulator is lithium niobate modulator.
56. optical transmitting set as claimed in claim 51, wherein said amplitude modulator are electricity absorption modulators.
57. optical transmitting set as claimed in claim 54, wherein said amplitude modulator are electricity absorption modulators.
58. optical transmitting set as claimed in claim 57, wherein said distributed feedback laser and described electricity absorption modulator are integrated on the same substrate.
59. optical transmitting set as claimed in claim 51, wherein the frequency modulation light source so that in described secondary signal, is the odd-multiple of π by the phase differential between two 1 of 0 separation of odd number by the first digital signal modulated.
60. optical transmitting set as claimed in claim 51, wherein said frequency modulation light source by described the first digital signal modulated so that the frequency displacement of described the second light signal between the bit rate frequency of described the first digital signal 25% and 75% between.
61. having the different time, optical transmitting set as claimed in claim 51, the signal of wherein said the first FM signal and the second amplitude modulation and frequency modulation distribute.
62. optical transmitting set as claimed in claim 51, wherein said the first digital signal has different time distributions with described digital signal.
63. optical transmitting set as claimed in claim 51, at least one in the phase delay between wherein said duration, rise time, fall time, adiabatic chirp, the amplitude modulation degree of depth and two the digital baseband signals is adjusted in order to increase described secondary signal to the dispersion tolerance of fibre-optical dispersion.
64. optical transmitting set as claimed in claim 49 also comprises spectra shaper, is used for receiving the signal of described the second amplitude modulation and frequency modulation.
65. a method that is used for light signal was passed Transmission Fibers, described method comprises:
Receive basic binary signal;
Utilize described basic binary signal operational light signal source to produce first signal, described first signal is frequency modulation;
Make described FM signal by spectra shaper in order to described first signal is shaped to secondary signal, described secondary signal is amplitude modulation and frequency modulation, comprises 1 and 0 with bit period; And
Make described secondary signal pass through Transmission Fibers;
Wherein, the bit period of described secondary signal and frequency displacement are π for making 1 phase differential by 0 separation of odd number.
66. such as the described method of claim 65, the frequency displacement of wherein said first signal be adjusted to so that the frequency displacement of described secondary signal equal described basic binary signal the bit rate frequency 1/2.
67. such as the described method of claim 65, the frequency displacement of wherein said first signal comprises the adiabatic chirp component.
68. such as the described method of claim 65, the frequency distribution of wherein said secondary signal is flat-top.
69. such as the described method of claim 65, it is π that the frequency displacement of wherein said first signal is used for making by 1 phase differential of 0 separation of odd number.
70. such as the described method of claim 65, it is π that the frequency displacement of wherein said first signal is used for making by 1 phase differential of 0 separation of odd number.
71. a method that is used for the transmission baseband signal, described method comprises:
Utilize baseband signal to produce FM signal; And
Provide amplitude modulator to be used for receiving described FM signal and be used for generating the signal of amplitude modulation and frequency modulation;
Wherein, to be used for making at the signal of described amplitude modulation and frequency modulation be π by 1 phase differential of 0 separation of odd number in the frequency displacement of described FM signal.
Applications Claiming Priority (17)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54823004P | 2004-02-27 | 2004-02-27 | |
| US60/548,230 | 2004-02-27 | ||
| US55424304P | 2004-03-18 | 2004-03-18 | |
| US60/554,243 | 2004-03-18 | ||
| US56606004P | 2004-04-28 | 2004-04-28 | |
| US60/566,060 | 2004-04-28 | ||
| US56773704P | 2004-05-03 | 2004-05-03 | |
| US60/567,737 | 2004-05-03 | ||
| US56976804P | 2004-05-10 | 2004-05-10 | |
| US56976904P | 2004-05-10 | 2004-05-10 | |
| US60/569,769 | 2004-05-10 | ||
| US60/569,768 | 2004-05-10 | ||
| US62175504P | 2004-10-25 | 2004-10-25 | |
| US60/621,755 | 2004-10-25 | ||
| US62974104P | 2004-11-19 | 2004-11-19 | |
| US60/629,741 | 2004-11-19 | ||
| PCT/US2005/006412 WO2005084268A2 (en) | 2004-02-27 | 2005-02-28 | Fm source and spectral reshaping element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101073210A CN101073210A (en) | 2007-11-14 |
| CN101073210B true CN101073210B (en) | 2013-04-17 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2005800127054A Expired - Fee Related CN101073210B (en) | 2004-02-27 | 2005-02-28 | Optical system including FM source and optical spectrum reshaper |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP1738504A4 (en) |
| JP (1) | JP4584304B2 (en) |
| CN (1) | CN101073210B (en) |
| CA (1) | CA2557150A1 (en) |
| WO (1) | WO2005084268A2 (en) |
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| CA2644078C (en) | 2006-03-03 | 2013-07-09 | Nokia Siemens Networks Gmbh & Co. Kg | Modulator device for generating an optical transfer signal modulated by means of a binary signal |
| JPWO2009001861A1 (en) * | 2007-06-25 | 2010-08-26 | 日本電信電話株式会社 | Optical modulation signal generation apparatus and optical modulation signal generation method |
| JP5182058B2 (en) * | 2008-12-16 | 2013-04-10 | 富士通株式会社 | WDM optical transmission method and WDM optical transmission system |
| US8340531B2 (en) * | 2009-12-18 | 2012-12-25 | General Instrument Corporation | Method and apparatus for improved SBS suppression in optical fiber communication systems |
| CN102780529B (en) * | 2012-07-13 | 2015-09-30 | 青岛海信宽带多媒体技术有限公司 | EPON and optical line terminal optical module thereof |
| CN105634614B (en) | 2014-10-30 | 2018-06-05 | 华为技术有限公司 | Optical sender, wavelength alignment methods and passive optical network |
| CN107431540A (en) * | 2015-03-27 | 2017-12-01 | 日本电气株式会社 | Optics receiving device |
| CN106792281B (en) * | 2015-11-20 | 2019-09-24 | 上海诺基亚贝尔股份有限公司 | Optical line terminal and optical network unit |
| CN108321675B (en) * | 2018-04-10 | 2019-12-17 | 青岛海信宽带多媒体技术有限公司 | laser and optical module |
| EP3824519A1 (en) * | 2018-09-17 | 2021-05-26 | Huawei Technologies Co., Ltd. | High power and high quality laser system and method |
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- 2005-02-28 WO PCT/US2005/006412 patent/WO2005084268A2/en active Application Filing
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Also Published As
| Publication number | Publication date |
|---|---|
| CA2557150A1 (en) | 2005-09-15 |
| CN101073210A (en) | 2007-11-14 |
| JP4584304B2 (en) | 2010-11-17 |
| JP2007525909A (en) | 2007-09-06 |
| EP1738504A2 (en) | 2007-01-03 |
| WO2005084268A3 (en) | 2007-02-01 |
| WO2005084268A2 (en) | 2005-09-15 |
| EP1738504A4 (en) | 2017-04-19 |
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