CN101237283B - There is directly modulation or the externally modulated laser optical transmission system of feed-forward noise elimination - Google Patents
There is directly modulation or the externally modulated laser optical transmission system of feed-forward noise elimination Download PDFInfo
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- CN101237283B CN101237283B CN200710307153.0A CN200710307153A CN101237283B CN 101237283 B CN101237283 B CN 101237283B CN 200710307153 A CN200710307153 A CN 200710307153A CN 101237283 B CN101237283 B CN 101237283B
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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
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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
-
- 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
-
- 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
- H04B10/58—Compensation for non-linear transmitter output
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- Computer Networks & Wireless Communication (AREA)
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- Nonlinear Science (AREA)
- Optics & Photonics (AREA)
- Optical Communication System (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The invention provides a kind of for generation of through optical modulation to be transferred to the optical launcher of remote receiver via optical fiber link, it comprises: laser; Be coupled to the input of described laser, it is for carrying out direct Modulation and Amplitude Modulation with RF signal to described laser, to produce the optical signalling comprised containing through the component of amplitude modulation information; And phase-modulator, its output being coupled to described laser is for reducing or eliminating the noise signal produced in described laser.
Description
Technical field
The present invention relates to a kind of optical transmission system for analog signal, and more particularly, relate to the solid-state laser of a kind of directly modulation or external modulation.In addition, the present invention relates to and eliminate by the many white noise component (white noise) that produces or the noises (itself and frequency change on the contrary, and are therefore commonly referred to " 1/f " noise) produced by the fluctuation in the bias current of laser or thermal environment of may originating of the Brownian movement etc. of such as charge carrier in semiconductor laser.
Background technology
The analog intensity of electricity consumption Signal shock light-emitting diode (LED) or semiconductor laser is considered to the most straightforward procedure for transmitting the analog signals such as such as voice and video signal on optical fiber known in technique.Although the advantage of this type of analogue transmission technology is to have significantly less bandwidth requirement compared with such as digit pulse code modulated or the Digital Transmission such as simulation or pulse frequency modulated, Modulation and Amplitude Modulation is used usually to propose comparatively strict requirement to the noise of reflector and distortion characteristic.
Due to these reasons, when being applied to employing and there is the short transmission link of the scattered optical fiber link penetrated, use directly modulation technology in conjunction with 1310nm laser.For being applied to metropolitan area and long-distance optical fiber transmission link, link low-loss requires the 1550nm laser using external modulation, generally extends over very long distance (100km) and high-frequency (more than 900MHz).The limiting factor of this type of link may be the conversion of the residual phase noise from laser, and described residual phase noise converts amplitude noise to via the scattering existed in optical fiber link.The present invention be therefore absorbed in that the noise that is provided for being associated with the phase noise of laser eliminates simple and the problem of low-cost system, make simulated optical export and can be used for metropolitan area and long-reach optics network, in particular for the analogue transmission of broadband RF signal.
The direct current modulation of laser becomes known for digit optical transmission system, such as dense wave division multipurpose (DWDM) system.Referring to " DWDMNetworks, Devices, andTechnology " (IEEEPress, the 2003,154th page) of (such as) Kartalopoulos.
Except to except the low noise figure required by 1550nm simulated optical transmission system, described system is also necessary for highly linear.Distortion intrinsic in specific simulating emitter stops linear electrical modulation signal to be optical signalling by linear transformation, but causes described distorted signals.These impacts are harmful especially for multi-channel video transmission, fabulous linear in case channel is interfering with each other of described multi-channel video transmission requirement.The simulated optical system of highly linearized is widely used in commercial analogue system, such as, broadcast TV transmission, CATV, interactive TV and visual telephone transmission.
To the linearizing research of optics and other non-linear reflector for some time, but proposed solution has shortcoming in practice.The bandwidth that major applications discussed above has is for excessive many actual embodiments.Complicated system component is needed, such as optical power combiner and multiple light source for linearizing feed-forward technique.Quasi-optics feed-forward technique suffers similar complexity problem, and needs the part mating fabulous in addition.But as discussed below, the forward direction technology eliminated for phase noise is the practical technique that the good technology of many exploitations can be used to implement.
As mentioned above, knownly in optical transmission system, external modulator is used in the prior art.5th, 699, No. 179 United States Patent (USP)s describe and a kind ofly bring out the external modulation of compound secondary (CSO) distortion component and feedforward linearized simulated optical reflector for reducing optical fiber.
Before making the present invention, not yet application is coupled to the phase-modulator of directly (electric current) modulated laser for the object eliminating the phase noise component produced by the various noise sources in the semiconductor structure of laser.It should be noted that semiconductor laser represents noise in its amplitude (being commonly referred to relative intensity noise) and its phase place.These noise characteristics have nothing to do with optical maser wavelength substantially, but noise can sentence different modes appearance at different wave length in single mode fibers transmission.The main inside of phase place and amplitude noise mechanism is caused to be spontaneous emission in the active region of laser.Because the photon of spontaneous emission does not have given phase relation with those photons produced via stimulated emission, thus the amplitude of gained light field and phase place are all affected.Spontaneous emission process is well-known, and has been shown as and is described by Brownian motion process, and wherein noise spectrum is constant (white noise) substantially in frequency of operation.At laser external, the environmental impacts such as such as microphone effect, temperature fluctuation and bias current noise also can produce phase noise in light field.These events cause light phase noise usually, and it represents the noise spectrum with " 1/f " correlation.The present invention manages to eliminate by feedforward the proper phase noise that minimizes from semiconductor laser and no matter the driving mechanism of noise is how.
Summary of the invention
1. goal of the invention
The object of the present invention is to provide a kind of improvement optical transmission system using directly modulation laser.
Another object of the present invention is to compensate for the noise in the laser of simulated optical transmission system.
Another object of the present invention is to provide a kind of outside MachZender modulator reduced to improve phase noise for 1550nm simulated optical transmission system.
Another object of the present invention is that providing a kind of is applicable to long distance dispersion optical fiber media and uses the highly linear simulated optical transmission system with the directly modulation laser of phase-correcting circuit.
Another object of the present invention is to provide a kind of phase-shift circuit for reducing the residual phase noise from laser in the simulated optical transmission system being applicable to long distance dispersion optical fiber media.
The present invention also aims to provide the phase noise compensation process in a kind of broadband analogue optical transmission system.
2. inventive features
In brief and put it briefly, the invention provides a kind of for generation of optical modulation for via the optical launcher of dispersion optical fiber link transmission to remote receiver, it has: input, for receiving the input of broadband analogue radiofrequency signal; Semiconductor laser, it is for generation of the optical signalling with the phase noise that is associated; And noise canceller circuit, it comprise optical phase modulator for reduce optical launcher export in phase noise and and then the distorted signals caused due to phase modulated noise component reducing that the receiver end place of optical fiber link presents.
On the other hand, the invention provides a kind of for the optical transmission system via dispersion optical fiber link, it comprises: the optical launcher with analog signal input; Semiconductor laser; Modulation circuit, for laser described in directly modulation; And phase offset circuit, for eliminating the optical phase modulation product be associated with external modulator for the optical signalling noise produced by semiconductor laser.
On the other hand, the present invention further provides a kind of low cost directly modulation technology, it preferably includes the circuit for control both optical phase-modulator, the phase noise component that described optical phase modulator produces for reducing laser.
In another aspect of this invention, a kind of noise canceller circuit for reducing phase noise in analog signal transmission is provided, output optical signalling from semiconductor laser is split into two paths by it, one lead to phase-modulator and another lead to frequency discriminator.Amplitude and phase place adjust described phase-modulation erasure signal to mate frequency or the phase place dependence of the phase noise of laser generation.The phase place of described signal by the delay in the one in described path or phase adjustment element synchronous.Then and secondary signal main by optical phase modulator restructuring only has amplitude-modulated single optical signalling to produce.Therefore, phase-modulator modulates the main signal from semiconductor laser in the mode minimizing gained phase noise, thus analog signal is suitable for via dispersion optical fiber link transmission.
According to this disclosure (comprise following be described in detail in) and by putting into practice the present invention, be understood by those skilled in the art that extra object of the present invention, advantage and novel feature.When hereafter describing of the present invention referring to preferred embodiment, the present invention should be understood and be not limited to this.What can obtain herein teaching those skilled in the art will realize that additional application in other field, amendment and embodiment, described additional application, amendment and embodiment belong in the scope of the invention that discloses in this article and advocate, and the present invention can have remarkable effectiveness relative to it.
Accompanying drawing explanation
In conjunction with the drawings referring to following detailed description, will understand better and comprehend these and other feature of the present invention and advantage, wherein:
Fig. 1 (a) is the height simplified block diagram of external modulation optical transmission system well known in the prior art;
Fig. 1 (b) is the height simplified block diagram of directly modulation optical transmission system well known in the prior art;
Fig. 2 is the height simplified block diagram according to optical transmission system of the present invention.
State novel feature of the present invention and characteristic in the dependent claims.But, by by reference to the accompanying drawings referring to the detailed description of specific embodiment being come to best understanding the present invention itself and further feature and advantage.
Embodiment
Now will describe details of the present invention, comprise its exemplary aspect and embodiment.Referring to the accompanying drawings and the description below, same reference numerals for identifying identical or intimate element, and wishes the principal character that one exemplary embodiment is described with the graphic mode highly simplified.In addition, do not wish that accompanying drawing describes each feature of practical embodiments or the relative size of institute's elements depicted, and accompanying drawing is not drawn in proportion.
Fig. 1 (a) is the block diagram utilizing the prior art optical launcher of external modulator as the the 5th, 699, No. 179 United States Patent (USP) represents.Described reflector (usually with 10 displayings) via fiber path 30 to receiver 60 transmitting optics signal.Reflector 10 comprises semiconductor laser 12, and it produces continuous wave (CW) and exports.The representative instance of this type of laser is distributed Feedback (DFB) laser and/or Fabry-Perot laser, and it produces output beam with the wavelength of 1,550nm.Unmodulated optical signalling from laser is coupled to modulator 16 by optical fiber 14.Modulator 16 can be that in the single modulator of such as Mach-Zehnder modulator, cascade MZ modulator or such as feedforward linearized circuit one is with modulator.Modulator 16 also receives broadband RF signal via terminal 18 and circuit 20, such as Modulation and Amplitude Modulation residual sideband (AM-SDB) cable TV (CATV) or vision signal.In addition, when using feedforward linearized circuit, provide to modulator 16 signal that depolarizes via terminal 22 and circuit 24.The described signal that depolarizes for depolarizing to the optics input of error correction modulator (not shown) in modulator 16.
What carry video data is coupled to amplifier 28 through optical modulation by optical fiber link 26.Amplifier 28 is erbium doped optic fibre amplifier (EDFA) normally.Optical signalling through amplifying is coupled to the optical fiber transmission line 30 towards receiver 60.Described optical fiber transmission line 30 can be the long-distance link extending past a few km.In the case, the line amplifiers such as such as EDFA28 can be provided with spacing distance wherein, described signal is boosted to required level along described circuit.At receiver 60 place, the amplifier optical signalling that (not shown) imports into boost also can be provided.Then the signal through boosting is applied to photoelectric detector and at receiver 60 place, its demodulation is made as the signal of telecommunication, the described signal of telecommunication represents original video or the data-signal at circuit 50 place.
Fig. 1 (b) is the block diagram of the prior art optical launcher of the direct current modulation utilizing laser.Wideband RF analog signal is applied directly to laser 12.Optical modulation from laser 12 is coupled to amplifier 28 by optical fiber link 26, such as EDFA.Optical signalling through amplifying is coupled to the optical fiber transmission line 30 towards receiver 60.At receiver place, convert optical signalling to the signal of telecommunication, the described signal of telecommunication represents original video or the data-signal at circuit 50 place.
Fig. 2 is the height simplified block diagram according to optical transmission system 100 of the present invention.Analog rf signal input source 101 (such as comprising the broadband signal of multiple channel) and predistortion circuit 105 is shown in figure.Come to carry out predistortion to the RF signal being applied to laser 102 rightly by using predistortion circuit 105, as known in the state of the art, be applied to the RF signal of laser with the nonlinear response affecting the signal at remote receiver place of compensate for laser for amendment.The output of predistortion circuit 105 is applied to laser 102 modulate it.The modulation of the laser 102 in the present invention can be AM-VSB modulator or quadrature amplitude modulator.The optical signalling of laser is exported 110 and splits into two parts: a part is applied to phase-modulator 111; Another part is applied to frequency identification circuit 115.
The edge emitting semiconductor laser used in Fig. 2 system is preferably distributed feedback laser (DFB), but can use Fabry-Perto (FP) laser equally.Distributed Feedback Laser is optimization approach, be mainly included in single zlasing mode, and the optical energy of FP laser is dispersed in the middle of many patterns because its optics exports.
In a preferred embodiment, described laser is the outside cavity gas laser of laser optical output wavelength within the scope of 1530 to 1570nm.In addition, broadband analog signal input has the bandwidth that is greater than an octave and comprises multiple dissimilarity information bearer channel.
Frequency is differentiated that the output of 115 is applied to circuit for signal conditioning 103, and described circuit 103 is made up of the tandem sequence circuit output RF signal of frequency discriminator being performed to distinct operation.RF signal is applied to attenuator 116 to adjust the amplitude of described signal rightly, matches with the amplitude of the phase deviation component introduced with the phase noise characteristic of laser 102.
The output of attenuator is then connected to phase offset circuit 117.Circuit 117 corrects the time lag compared with the described signal being applied to modulator 111 of the signal output being applied to circuit element 115,116,117.In paid close attention to transmission of video frequency band (be 50MHz-1000MHz for traditional C ATV system), the phase noise of semiconductor laser is " in vain ", and namely the spectral power density of noise and frequency have nothing to do.In the case, needs are had constant (adjustable) gain by phasing path, its postpone just in time with the delay matching of predominating path.Need the aspect illustrated to be frequency discriminator, the optics specifically in phasing path is to electricity transfer process.When photodiode detects optical signalling, observe the phenomenon being called shot noise.This noise is produced with the statistic processes producing electron-hole pair by absorb photons in the photodiode.This noise is inevitable for all practical purposes.Therefore, shot noise will form lower limit to attainable phase noise amount of cancellation.
Then the output of phase offset circuit 117 is applied to phase-modulator 111, with so that phasing is incorporated in optical signalling with so that correct or compensate the noise that produces.
Be given as from the Spectral Noise Density of the photoelectric current of photodiode generation
<i
n 2>＝2eI
p
Wherein e is electron charge and I
pit is DC photoelectric current.Those skilled in the art will recognize such fact immediately: noise power has linear dependence to received optical power, and is therefore improved along with the increase of institute's received power by the signal to noise ratio of the process of shot noise domination.Basic Design in the proposed invention of this representative is traded off.Be switched to more power in phasing path by with the Optical output power of reflector for cost is eliminated to improve final noise.
The output of modulator 111 is coupled to amplifier 113 via optical fiber 112, and described amplifier 113 is then connected to optical fiber or link 114.At far-end, optical fiber or link 114 are connected to receiver, and received optical signalling is converted to RF signal by described receiver.
Without departing from the spirit and scope of the present invention, it will be apparent to those skilled in the art that many changes and amendment.For example, although be described and illustrate in the context of TV signal madulation laser or light-emitting diode, the inherent distortion of other non-linear devices such as such as amplifier can be eliminated to a great extent by this technology.The precision adjustment of the relative phase of the signal mainly and in secondary path is in secondary path in the illustrated embodiment, but this also can in the predominating path with rough adjustment.Secondary path is preferred, because this type of delay in predominating path may have inappropriate impedance to this path.
The various aspects of technology of the present invention and device can be implemented in digital circuit or computer hardware, firmware, software or its combination.Circuit of the present invention can be implemented or above implement at the software (it automatically or as required can download to computer product) being positioned at network node or website place in computer product (it is visibly implemented in machine-readable storage device and performs for programmable processor).Aforementioned techniques can be performed by the gate array of (such as) single central processing unit, multiprocessor, one or more digital signal processors, gate or hard-wired logic, and described device is for performing a sequence signal or instruction repertorie to perform function of the present invention by operating input data and produce output.Described method can advantageously be implemented in one or more computer programs that can perform on programmable system, and described programmable system comprises at least one through coupling to receive data and instruction from data-storage system and to the programmable processor of data-storage system transmission data and instruction, at least one input/output device and at least one output device.Each computer program can optionally be implemented with advanced procedures or OO programming language or with compilation or machine language; And under any circumstance, described language can be compiling or interpreter language.For example, suitable processor comprises general purpose microprocessor and special microprocessor.In general, processor will receive instruction and data from read-only memory and/or random access memory.The storage device being suitable for visibly implementing computer program instructions and data comprises the nonvolatile memory of form of ownership, for example comprises: semiconductor device, such as EPROM, EEPROM and flash memory device; Disk, such as internal hard drive and removable dish; Magneto optical disk; And CD-ROM dish.Any aforementioned means can be supplemented by specially designed application-specific integrated circuit (ASIC) (ASIC) or be incorporated in ASIC.
To understand, each in said elements or both or both above structures that together also effectively can be applied to other type different from the above-mentioned type.
Although the present invention illustrated and be described as implementing in optical transmission system, do not wish that it is limited to shown details, because various amendment and structural change can be made when departing from spirit of the present invention never in any form.
When not doing to analyze further, foregoing teachings so will represent main points of the present invention comprehensively, other people are easily adjusted for various application it when not being omitted in the feature of intrinsic propesties prior art position forming completely the general or particular aspects of the present invention by application current knowledge, and therefore this type of adjust should and in the hope equivalence meaning that is included in appended claims and scope.
Claims (17)
1. for generation of through optical modulation to be transferred to an optical launcher for remote receiver via optical fiber link, it comprises:
Laser, it is for generation of the base band optical signalling of the noise expansion comprised on frequency spectrum;
Modulator, it is for carrying out directly modulation with analog rf signal to described laser, contains through the component of amplitude modulation information and the optical signalling of phase-modulated component to produce to comprise;
Phase-modulator, its output being coupled to described laser is to receive a part for described optical signalling, and the phase noise that operation is associated with described optical signalling for reduction with receiving phase modulation eliminating signal; And
Phase-correcting circuit, its described output being coupled to described laser is to receive another part of described optical signalling, described phase-modulator is coupled in the output of described phase-correcting circuit, and described phase-correcting circuit operation is to produce described phase-modulation erasure signal
Wherein, described phase-correcting circuit comprises the frequency discriminator of the input of the described another part with the described optical signalling that coupling exports from described laser with reception, so that the biased electrical signal phase-modulated component in described optical signalling be converted to for biased described phase-modulator is eliminated there is effective noise
Wherein said phase-correcting circuit comprises the photodiode being coupled to described frequency discriminator.
2. reflector according to claim 1, wherein said laser is semiconductor laser, and described phase-modulator is the external module separated with described semiconductor laser.
3. reflector according to claim 1, wherein said phase-modulator increases the SBS threshold value of the optical signalling that described remote receiver place receives.
4. reflector according to claim 1, the wavelength of the described optical signalling wherein exported from described laser 1530 within the scope of 1570nm.
5. reflector according to claim 1, wherein said RF signal is broadband analog signal, and it has the bandwidth that is greater than an octave and comprises multiple dissimilarity information bearer channel.
6. reflector according to claim 1, it comprises predistortion circuit further, its nonlinear response of receiving optical signal for revising the described RF signal that is applied to described laser and receiving at described remote receiver place with the impact compensating described laser.
7. reflector according to claim 1, the more power being wherein switched to described phase-correcting circuit by with the Optical output power of described reflector for cost is eliminated to improve final noise.
8. reflector according to claim 1, is modulated to quadrature amplitude modulation described in wherein said laser.
9. reflector according to claim 1, wherein said phase-correcting circuit comprises the circuit for signal conditioning of the output being coupled to described frequency discriminator.
10., for generation of an optical launcher for the optical modulation for being transferred to remote receiver via optical fiber link, it comprises:
Laser, it is for generation of the base band optical signalling of the noise expansion comprised on frequency spectrum;
Modulator, it is for carrying out direct Modulation and Amplitude Modulation with analog rf signal to described laser, contains through the component of amplitude modulation information and the optical signalling of phase noise to produce to comprise; And
Phase-modulator, its output being coupled to described laser is to receive the Part I of described optical signalling, and described phase-modulator is for reducing the phase noise be associated with described optical signalling; And
Biasing circuit, its described output being coupled to described laser is to receive the Part II of described optical signalling, the described Part II of described optical signalling is converted to the signal of telecommunication, and be coupled to described phase-modulator to control described phase-modulator based on the described signal of telecommunication, be reduced in the phase noise in receiving optical signal that remote receiver place receives thus
Wherein, described biasing circuit contain be coupled to described laser output to receive the frequency discriminator of the described Part II of described optical signalling to there is effective noise elimination in the biased electrical signal phase-modulated component in described optical signalling be converted to for biased described phase-modulator.
11. reflectors according to claim 10, wherein said laser is semiconductor laser, and the noise characteristic of wherein said laser introduces described phase noise.
12. reflectors according to claim 10, wherein said phase-modulator increases the SBS threshold value of the receiving optical signal that described remote receiver place receives.
13. reflectors according to claim 10, wherein said biasing circuit contains and is coupled to described frequency discriminator output to regulate the attenuator of the amplitude of described frequency discriminator output and in order to the described Part II of the described optical signalling making the to be supplied to described phase-modulator phase shift element synchronous relative to the time lag of the described Part I of described optical signalling.
14. reflectors according to claim 10, the wavelength of the described optical signalling wherein exported from described laser is between 1530nm to 1570nm.
15. reflectors according to claim 10, wherein said RF signal is broadband analog signal, and it has the bandwidth that is greater than an octave and comprises the channel of multiple different carry information.
16. reflectors according to claim 10, it comprises predistortion circuit further, its described nonlinear response through receiving optical signal received at described remote receiver place with the impact compensating described laser for revising the described RF signal that is applied to described laser.
17. reflectors according to claim 10, the reduction of the phase noise that the controlled adjustment of wherein said biasing circuit is associated with described optical signalling.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11/701,742 US7881621B2 (en) | 2006-03-02 | 2007-02-02 | Optical transmission system with directly modulated laser and feed forward noise cancellation |
| US11/701,742 | 2007-02-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101237283A CN101237283A (en) | 2008-08-06 |
| CN101237283B true CN101237283B (en) | 2016-02-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN200710307153.0A Expired - Fee Related CN101237283B (en) | 2007-02-02 | 2007-12-27 | There is directly modulation or the externally modulated laser optical transmission system of feed-forward noise elimination |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP5512090B2 (en) |
| KR (1) | KR20080072520A (en) |
| CN (1) | CN101237283B (en) |
| TW (1) | TW200835182A (en) |
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| JP5424939B2 (en) * | 2010-03-01 | 2014-02-26 | 日本電信電話株式会社 | Optical phase noise suppression circuit, phase fluctuation detection circuit, and phase fluctuation detection method |
| CN103575408B (en) * | 2013-10-29 | 2017-04-12 | 桂林电子科技大学 | Coherent light detection system and method for optical fiber delay line phase control |
| JP6232334B2 (en) * | 2014-04-17 | 2017-11-15 | 日本電信電話株式会社 | Laser phase noise reduction device |
| CN112393692B (en) * | 2019-08-14 | 2023-04-28 | Oppo广东移动通信有限公司 | Laser projection module, image acquisition module, depth camera and electronic equipment |
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| GB8602017D0 (en) * | 1986-01-28 | 1986-03-05 | British Telecomm | Reducing fluctuations in radiation beam characteristic |
| US7848661B2 (en) * | 2005-03-15 | 2010-12-07 | Emcore Corporation | Directly modulated laser optical transmission system with phase modulation |
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2007
- 2007-12-10 TW TW096147089A patent/TW200835182A/en unknown
- 2007-12-27 CN CN200710307153.0A patent/CN101237283B/en not_active Expired - Fee Related
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| TW200835182A (en) | 2008-08-16 |
| CN101237283A (en) | 2008-08-06 |
| JP2008193709A (en) | 2008-08-21 |
| KR20080072520A (en) | 2008-08-06 |
| JP5512090B2 (en) | 2014-06-04 |
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