CN101873169A - Receiving system in wireless optical communication and signal receiving method thereof - Google Patents
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Abstract
The invention relates to a receiving system in wireless optical communication and a signal receiving method thereof, and belongs to the field of optical communication. The system comprises a group of focusing lenses, a group of fiber or waveguide array, a group of optical signal delayers, a group of optical phase modulators, an optical coupler, an optical filter, a photoelectric detector, an analysis and calculation control module and a decoding and sampling judgment module. The method comprises the following steps of: 1) focusing and feeding spacial optical signals into a fiber array by adopting the group of focusing lenses; 2) performing phase delay and phase modulation on each path of the fiber array, and coupling-out a path of optical signals; 3) filtering the optical signals, converting the optical signals into electric signals, and outputting the electric signals to the decoding and sampling judgment module and the analysis and calculation control module respectively; and 4) in a communication time slot, restoring original information from the received electric signals by using the decoding and sampling judgment module, and in a reference time slot, performing feedback adjustment on each path of received optical signals by using the analysis and calculation control module. The receiving system and the signal receiving method thereof have the advantages of easy implementation and high precision.
Description
Technical Field
The present invention relates to a receiving system for long-distance Wireless Optical Communication (abbreviated as WOC), and more particularly, to a receiving system in Wireless Optical Communication and a signal receiving method thereof, and belongs to the field of Optical Communication.
Background
In recent years, wireless communication is rapidly developed, wireless users are gradually increased year by year, services are more diversified, and data services are rapidly increased, so that the requirement that broadband wireless signals and carrier frequencies are expanded to high frequencies is increasingly urgent. Under such a demand, wireless optical communication is receiving more and more attention as an extension of radio frequency wireless communication in an optical frequency domain, and becomes one of the key technologies of future ultra-wideband wireless communication. Compared with the traditional radio frequency wireless communication, the carrier wave of the wireless optical communication is not a radio frequency signal but a higher frequency optical signal. The wireless optical communication not only has a plurality of advantages of radio frequency wireless communication, namely convenient establishment, difficult terrain limitation, smaller weight and volume, suitability for mobile application, but also is more superior in a plurality of aspects, namely rich frequency resources and no legal control; the emission signal and other electronic devices cannot interfere with each other; the signal directive property is high, and the wave beam is dispersed for a short time, and energy utilization is high and the signal is difficult to be intercepted, and the security is high. With the development of optoelectronics and the progress of micromachining technology, optical antennas, light sources and the like can have smaller volume and weight than radio frequency antennas and radio frequency sources, and are more suitable for vehicle-mounted, ship-mounted, satellite-mounted and other applications. However, since the optical wavelength is shorter and the diffraction effect is not significant, the optical signal is more attenuated in the atmosphere and is more affected by the weather environment than the radio frequency wireless communication. Therefore, long-distance wireless optical communication technically requires higher receiving sensitivity.
A conventional wireless optical communication receiving scheme is shown in fig. 1, and the receiving system mainly includes a tracking aiming control module 2 and a signal receiving processing module 3. The tracking and aiming control module 2 mainly comprises an ultra-wide view field focusing lens 1, a filter device 5 (used for filtering interference light signals out of a 1550nm communication light frequency band), a CCD photoelectric detector array 6 and a calculation and control unit 7, and the function of the tracking and aiming control module is to calculate the relative position of a transmitting party by analyzing the angle of an incident beam, so that the direction of a universal joint 9 is adjusted, a receiving surface of a signal receiving and processing system can be aligned to the direction of the incident signal beam, and the receiving efficiency is ensured. The specific working process is as follows: after being captured by a focusing lens 1, a spatial signal light beam emitted by a transmitting user is further focused by a telecentric imaging lens 4 so as to reduce an included angle between the light beam and a lens main shaft and a filter main shaft, and then a filter device 5 is used for inhibiting background light noise, and then the spatial signal light beam is imaged on a CCD detector array 6 at a receiving end. The CCD detector array converts the optical signals into electrical signals, which are sent to a computing and control unit. When the incident angle of the incident light beam is different, the position of the incident light beam imaged on the CCD is also different, so that the calculation and control unit has the functions of: firstly, the incident angle and the wavefront shape of an incident beam can be calculated in real time by analyzing the imaging position and the imaging shape detected on the CCD area array; and secondly, correspondingly controlling the rotation of the universal joint through the calculation result of the angle and the shape of the incident beam so as to adjust the direction of the transmitting/receiving machine aligned to the incident beam and feed back an optical signal to the opposite user node. The signal receiving and processing module 2 mainly comprises an ultra-wide field focusing lens 1, a filter 5, a photoelectric detector 10 and an electric signal sampling and judging module 11. After the receiving plane of the receiver is perpendicular to the direction of the incident light signal under the adjustment of the tracking and aiming control module, the light signal is captured by a focusing lens 1 in the signal receiving and processing module, the out-of-band noise light signal is filtered by a filter device 5, then the out-of-band noise light signal is incident on a photoelectric detector 10 and is converted into an electric signal, and then the required digital electric signal is obtained through an electric signal sampling and judging module.
However, the performance of this conventional wireless optical communication reception scheme is limited to several. First, in long-distance wireless optical communication applications, such as inter-satellite optical communication and satellite-to-ground optical communication, due to the long propagation distance, the large beam divergence, the small received power per unit area, and the limited receiving area of the focusing lens, the received signal is very weak, which puts high demands on the receiving sensitivity of the photodetector and the noise suppression capability of the filter. Secondly, if in order to improve the received signal power, an oversized focusing lens can be adopted to realize large-aperture light beam capture, but the processing technology of the large lens is very difficult, the processing cost is too high, the volume and the weight are large, the integration level is low, and the large lens is difficult to be applied to the occasions of satellite-borne, ship-borne and the like. Meanwhile, when a large aperture is received, after the light fields on the receiving surface are converged, signal fading during synthesis on the photoelectric detector may be caused by inconsistent phases of the light fields at different positions on the receiving aperture. Thirdly, the related research of the spatial filter in the conventional receiving scheme is not yet mature, the bandwidth of the common interference filter is large (usually tens of nm, preferably 0.2-0.3nm), but the common interference filter only enters the optical field of the filter along the collimation axis, if the incident angle is increased, the central wavelength of the filter is shifted, the bandwidth of the filter is increased, the peak transmittance is reduced, the noise power passing through the filter is increased, and the receiving quality is reduced. Some research organizations both abroad and abroad have developed experimental faraday type anomalous Dispersion Optical Filter (FADOF) and foctor anomalous Dispersion Optical Filter (VADOF), equivalent noise bandwidths of 0.02nm (s.bloom, v.chan and c.s.liu, "High-level iterative estimation of BMDO laser system 1.1 Gbit/s", proc.of spf.1995, vol.2381: 113-.
Disclosure of Invention
In view of the defects in the prior art, the present invention aims to provide a receiving system in wireless optical communication and a signal receiving method thereof, and the system is a wireless optical communication receiving system structure based on array receiving and coherent combining, which has high technical maturity, high integration level and better performance.
The technical scheme of the invention is as follows:
a wireless optical communication receiving system based on array receiving and coherent combination comprises a group of focusing lenses, a group of optical fiber or waveguide arrays, a group of optical signal delayers, a group of optical phase modulators, an optical coupler, an optical filter, a photoelectric detector, an analysis calculation control module and a decoding sampling judgment module.
The focusing lens is placed at the front end of the optical fiber or waveguide array and used for focusing and feeding a space optical signal into the optical fiber or waveguide array.
Each path of the optical fiber or waveguide array is respectively connected with the input end of one optical signal delayer;
the output end of each optical signal delayer is connected with the input end of one optical signal phase modulator through a waveguide or an optical fiber;
the output end of each optical signal phase modulator is respectively connected with one input end of the optical coupler through a waveguide or an optical fiber;
the output end of the optical coupler is connected with the input end of the optical filter through an optical fiber or a waveguide;
the output end of the optical filter is connected with the input end of the photoelectric detector through an optical fiber or a waveguide;
the output end of the photoelectric detector is connected with the input end of the analysis calculation control module and the input end of the decoding sampling judgment module through a circuit;
the output end of the analysis calculation control module is respectively and electrically connected with the electric signal control end of each optical signal delayer and the electric signal control end of each optical phase modulator.
Further, the optical signal delayer is an optical fiber adjustable true delayer or a true delay module based on slow light effect.
Further, the optical signal phase modulator is an electro-optical modulator based on a waveguide or an electric control piezoelectric ceramic true delay phase controller based on PZT.
Further, the optical filter is a photonic crystal fiber filter.
Further, the output end of the optical filter is connected with an EDFA through an optical fiber or a waveguide; the EDFA is connected with the input end of the photoelectric detector through an optical fiber or a waveguide.
A receiving system signal receiving method in wireless optical communication comprises the following steps:
1) focusing the spatial light signal by using a group of focusing lenses and feeding the spatial light signal into an optical fiber or waveguide array;
2) each path of the optical fiber or the waveguide array is subjected to phase delay through an optical signal delayer respectively;
3) respectively carrying out phase modulation on each path of phase-delayed signals by an optical signal phase modulator, and then coupling and outputting the signals into a path of optical signals;
4) filtering the processed optical signals, converting the filtered optical signals into electric signals, and outputting the electric signals to a decoding sampling judgment module and an analysis calculation control module respectively;
5) in a communication time slot, the decoding sampling judgment module recovers original information from a received electric signal;
6) and in a reference time slot, the analysis calculation control module performs feedback adjustment on the optical signal delayer and the optical signal phase modulator.
Further, the analysis calculation control module takes the average amplitude of the received electrical signals as a target variable, takes the control electrical signals of the optical signal delayer and the control electrical signals of the optical signal phase modulator in each path as regulation variables, and performs feedback adjustment on the optical signal delayer and the optical signal phase modulator.
Further, the output end of the optical signal delayer is connected with the input end of the optical signal phase modulator through a waveguide or an optical fiber; the output end of each optical signal phase modulator is connected with one input end of the same coupler through a waveguide or an optical fiber.
Further, an optical filter is adopted for filtering processing, and the optical filter is connected with the output end of the coupler through a waveguide or an optical fiber; the output end of the optical filter is connected with the input end of a photoelectric detector through a waveguide or an optical fiber to convert an optical signal into an electric signal.
Further, a nested neighborhood optimization algorithm is adopted to perform feedback adjustment on the optical signal delayer and the optical signal phase modulator; the neighborhood optimization algorithm is a climbing algorithm or a simulated annealing algorithm.
Compared with the prior art, the positive effects of the invention are as follows:
the wireless optical communication receiving scheme based on array receiving and coherent combining can easily realize a wireless optical communication receiving system with high sensitivity, high integration and easy expansion. It has the following advantages:
(1) the lens array is adopted to replace a light beam capturing mode of adopting a large lens in the traditional receiving scheme of wireless optical communication, on one hand, the requirement on the processing technology is reduced, so that the cost is reduced, meanwhile, the system integration level and the structural flexibility are improved, the expandability is better, and the weight, the volume, the receiving quality and the like of the system can be adjusted by increasing or reducing the scale of the array.
In the field of satellite-borne and ship-borne wireless optical communication, the weight and the volume of communication equipment are often strictly limited. In the conventional wireless optical communication receiving scheme, a single large-field focusing lens is adopted for beam capture, and special lens size design is required for specific system requirements. Because optical signals are weak in long-distance communication, a large lens receiving aperture is needed to improve the power of received optical signals, and the size of the needed lens can even reach the meter order. Meanwhile, the shape error of the lens influences the imaging phase difference of the light beam on the CCD detection array, so that the calculation accuracy of the tracking and aiming control module on the incoming light direction is influenced, and the lens processing technology level is higher in requirement. Therefore, in the conventional scheme, the high-precision and large-caliber focusing lens causes the system to have higher weight, volume and cost and poor expandability.
After the array receiving scheme of the invention is adopted, each lens can have a smaller receiving area due to the adoption of the lens array for receiving. Since the light beam is captured and enters the optical fiber or waveguide without being used for spatial imaging, and is subjected to adaptive adjustment by the optical signal delay device and the optical signal phase modulator, there is no specific requirement for the shape of each lens except for the requirement that the spatial light beam can be fed into the waveguide or optical fiber. The requirements on the lens processing technology are greatly reduced by the two points, so that the system cost is reduced. Meanwhile, each lens in the array works independently, so that the performance of a single lens cannot cause great influence on the whole system, each lens can be independently replaced and adjusted, the array scale can be increased or reduced, and the flexible adjustment of the weight, the volume and the receiving quality of the system can be realized.
(2) By means of array receiving and coherent combination, the signal-to-noise ratio of the received signals is greatly improved through consistent superposition of optical signals.
With a conventional wireless optical communication receiving scheme, that is, a single lens is used to capture a light beam, assuming that the total signal light that can be obtained on a receiving surface can be expressed as:
S(t)＝A·C(t)·cos(ωt+β) (1)
where c (t) is an electrical signal modulated by OOK on-off keying modulation, and c (t) is 0 or 1. Assuming that the total power of signals obtained in the receiving area is P, the total power of noise signals obtained is n (t), and the total power of noise is Pn. Then
However, in the receiving scheme of array receiving and coherent combining according to the present invention, assuming that the array scale is N, that is, an array composed of N lenses is used to replace a single focusing lens in the conventional scheme, and gaps between collimator units are ignored, that is, it is considered that a receiving area covered by the array composed of N lenses is equal to a receiving area covered by the single focusing lens in the conventional scheme, then the power of signal light captured by each lens should be:
P′＝P/N (3)
the optical signal captured by each lens can be expressed as:
Sk(t)＝Ak·C(t+Δtk)·cos(ωt+βk)，k＝1，2，3，...，N (4)
the power taken by each fiber is then:
the compound of the formula (3) can be obtained,
and the noise light signal captured by each lens is set to nk(t) power of
Pnk＝Pn/N (7)
Through the adjustment of optical phase and signal delay, the signals of each path realize the consistency of phase and signal delay, i.e.
Sk(t)＝Ak·C(t+ΔT)·cos(ωt+Δβ) (8)
Therefore, the optical signals are obtained by combining the branch signals through the coupler
The average power of the received optical signal is
Due to the randomness and the mutual independence of the noise, the total power of the synthesized noise signals of each branch is as follows:
as can be seen from the above derivation, according to the scheme of array reception and coherent synthesis of the present invention, the optical signal captured by the array is synthesized by N lenses, the synthesized signal optical power is N times higher than that obtained by a single focusing lens in the conventional reception scheme, and meanwhile, the synthesized noise optical power is kept unchanged from that received by the conventional reception scheme, so that the signal-to-noise ratio is finally N times higher.
(3) Compared with a spatial optical filter in a traditional wireless optical communication receiving scheme, the optical filter based on optical fiber or waveguide connection is adopted, on one hand, the central wavelength cannot change along with the change of the incident angle, and on the other hand, the narrower bandwidth and the higher peak transmittance can be realized.
The spatial optical filter device used in the conventional wireless optical communication reception scheme is generally of the interference filter type, the atomic filter type, or the like. The interferometric Filter technology is mature, and many commercial products have appeared, which have the disadvantage of large bandwidth (usually tens of nm, as small as 0.2-0.3nm), and the atomic filters also include two types, Faraday type Anomalous Dispersion Optical Filter (FADOF) and foctor Anomalous Dispersion atomic Filter (VADOF), which have small equivalent noise bandwidth (less than 0.01nm), but the technology is not mature, and most of them are still in experimental research stage. Also, another serious disadvantage of the spatial filter device is that as the incident angle of the light beam increases, the center wavelength of the filter shifts and the peak transmittance decreases, resulting in a decrease in the signal optical power passing through the filter, an increase in the noise optical power, and a deterioration in the signal-to-noise ratio.
In the present invention, on-line optical filters based on optical fiber or waveguide connections are used, and the related research in this field has been very mature, and a large number of high-performance commercial devices have appeared. The bandwidth of a common optical fiber interference type optical filter can reach 0.1nm magnitude, and an optical filter designed by utilizing the photonic crystal can even reach 0.0001nm magnitude. Meanwhile, as the optical signal is transmitted in the optical fiber or the waveguide, the condition that the central wavelength of the optical filter device is shifted due to different incident angles does not exist, and the fluctuation of signal power and signal to noise ratio does not exist. Therefore, the optical filter based on the optical fiber or waveguide connection has more choices in the selection of the optical filter, can select the filter with narrower bandwidth and higher performance, and is insensitive to the incident angle of the space light beam and has better stability.
(4) After the focusing lens captures the signal, optical fiber or waveguide is adopted for optical signal transmission, so that the instability of space transmission in the traditional wireless optical communication receiving scheme is avoided. And as the research on devices based on optical fibers or waveguides in optical fiber communication is very mature, more functions and higher performance can be realized by utilizing various mature devices.
In the traditional scheme, after being captured by a focusing lens, a light beam is incident on a CCD detection array through a telecentric imaging lens and a filter device in a space transmission mode, so that the positions and angles of the lens, the filter device, the CCD array and other devices are required to have higher accuracy. The scheme provided by the invention adopts an optical fiber or waveguide and other on-line transmission modes, so that higher integration level and stability can be realized. Meanwhile, the wavelength division multiplexing of a receiving end can be realized by utilizing the existing WDM device in the optical fiber communication, so that the communication frequency is expanded, the bandwidth utilization rate is improved, and the communication speed is finally improved; the existing EDFA amplifier can be used for realizing the amplification of a weak light signal at the front end of a photoelectric detector, thereby improving the receiving sensitivity of the system.
Drawings
Fig. 1 is a schematic diagram of a conventional receiving scheme for wireless optical communication;
wherein the device names denoted by numerical ordinals in the figures are:
1-focusing lens, 2-tracking aiming control module, 3-signal receiving and processing module,
4-telecentric imaging lens, 5-narrow band filter, 6-CCD area array,
7-calculation and control circuit, 8-motor drive circuit, 9-universal joint,
10-photoelectric detector, 11-electric signal sampling decision module
FIG. 2 is a schematic diagram of a receiving scheme of a wireless optical communication array receiving and coherent combining;
wherein the device names denoted by numerical ordinals in the figures are:
21-phase modulator array, 22-optical signal delay array, 23-optical coupler,
24-optical filter, 25-photodetector, 26-analysis calculation and control unit,
27-decoding, sampling, decision module
FIG. 3 is a time slot diagram of optical signals required in the wireless optical communication array receiving and coherent combination receiving scheme
Wherein the signals denoted by numerical sequence numbers in the figures are:
31-communication time slot, transmitting optical signal carrying original information
32-adjustment of time slots, transmitting optical signals carrying periodic square-wave signals
FIG. 4 is a flow chart of a nested optimal adjustment algorithm for signal delay and phase delay adjustment of each branch in an array receiving and coherent combining receiving scheme based on a "climbing" algorithm
FIG. 5 is a flow chart of an inner phase optimization tuning process in a nested optimization tuning algorithm.
Detailed Description
The structure of the wireless optical communication receiving system based on array receiving and coherent combination provides a receiving scheme with high sensitivity and high integration level for wireless optical communication. The principle structure is shown in fig. 2, and comprises:
and the focusing lens array is used for coupling the spatial optical signal into the optical waveguide array or the optical fiber array.
An optical waveguide array or an optical fiber array is used as a transmission path of the received optical signal. The output end of the optical waveguide array or the optical fiber array is connected with a group of optical signal delayers 21. The optical signal delayer can be a commercial optical fiber adjustable true delayer or a true delay module based on slow light effect, and is used for adjusting the signal delay of each optical signal, so that the electrical signal code elements carried by each optical signal are basically aligned. The output of each optical signal delay 21 is connected to the input of a set of optical phase modulators 22 by optical fibers or waveguides. The optical signal phase modulator can be an electro-optical modulator based on a waveguide, and can also be an electric control piezoelectric ceramic true delay phase controller based on PZT, and is used for adjusting the signal phase of each path of optical signal, so that coherent superposition of consistent phases of each path of optical signal can be realized. The output of each phase modulator is connected to a plurality of inputs of an optical coupler 23 via optical fibers or waveguides. The optical coupler 23 may be a waveguide-based or fiber-based structure for coherent combining of the optical signals. The output of the optical coupler 23 is connected via an optical filter 24 to the input of a photodetector 25 via an optical fiber or waveguide. The photodetector 25 converts the synthesized optical signal into an electrical signal. The output end of the photodetector 25 is electrically connected with the input ends of the electric signal decoding, sampling and judging module 27 and the calculation control module 26. The decoding and sampling decision module 27 is composed of a decoding circuit of the electrical signal and a sampling decision circuit, and is used for extracting original information from the electrical signal output by the photodetector. The analyzing, calculating and controlling module 26 is composed of an analyzing circuit and a controlling circuit, and an output end thereof is connected to the electric signal control ends of the optical signal delayers 21 and the optical signal phase modulators 22, and is used for analyzing and calculating information such as signal consistency and phase consistency of the optical signals of each path from the electric signals output by the photoelectric detectors, and generating feedback signals according to the calculation result and sending the feedback signals to the optical signal delayers 21 and the optical signal phase modulators 22, and controlling the feedback signals to enable the delays of the optical signal phases of each path and the carried electric signals to tend to be consistent.
The receiving scheme of array receiving and coherent combination in the wireless optical communication is characterized in that the analysis computer control scheme of each path of optical signal phase and carried electric signal delay is as follows:
the transmitting side inserts a section of square wave periodic signal in the transmitted electrical signal in a time division manner as a reference signal to obtain a time division composite signal as shown in fig. 3, and modulates the signal onto an optical signal to transmit the optical signal into a free space. The receiver captures and receives the signal. When the receiving system is in a communication time slot, the decoding and sampling decision module 27 of the receiving system starts to work, and processes the signal output by the photoelectric detector such as decoding, sampling, decision and the like, so as to recover the original information. When the time slot of the reference signal is in use, the analysis calculation control module 26 of the receiving system starts to work, the average power of the optical signal obtained by combining the reference optical signals of each path, that is, the average amplitude of the output signal of the photoelectric detector is used as a target variable, the control electric signals of each optical signal delayer and each optical signal phase modulator are used as regulation variables, and the delay and the phase of each optical signal tend to be consistent through the feedback regulation by the nested neighborhood optimization algorithm. The neighborhood optimization algorithm can adopt a 'climbing' algorithm or a rapid algorithm such as a simulated annealing algorithm and the like. The nested optimization algorithm based on the "climbing" algorithm is shown in the flowchart of fig. 4, and the "nesting" means that the 5 th step in the optimization algorithm, namely the process of adjusting the phase of each optical signal, is also a "climbing" optimization process, and the specific steps are shown in the flowchart of fig. 5. Through continuous feedback adjustment of the analysis calculation control module in the reference signal time slot, the receiving system can adapt to the current incident wavefront shape, the coherent superposition of each path of optical signal is ensured, and meanwhile, the electric signals carried by each path of optical signal can be synthesized uniformly.
Claims (10)
1. A receiving system in wireless optical communication is characterized by comprising a group of focusing lenses, a group of optical fibers or waveguide arrays, a group of optical signal delayers, a group of optical phase modulators, an optical coupler, an optical filter, a photoelectric detector, an analysis calculation control module and a decoding sampling judgment module; wherein,
the focusing lens is arranged at the front end of the optical fiber or waveguide array and is used for focusing and feeding a space optical signal into the optical fiber or waveguide array;
each path of the optical fiber or waveguide array is respectively connected with the input end of one optical signal delayer;
the output end of each optical signal delayer is connected with the input end of one optical signal phase modulator through a waveguide or an optical fiber;
the output end of each optical signal phase modulator is respectively connected with one input end of the optical coupler through a waveguide or an optical fiber;
the output end of the optical coupler is connected with the input end of the optical filter through an optical fiber or a waveguide;
the output end of the optical filter is connected with the input end of the photoelectric detector through an optical fiber or a waveguide;
the output end of the photoelectric detector is respectively and electrically connected with the input end of the analysis calculation control module and the input end of the decoding sampling judgment module;
the output end of the analysis calculation control module is respectively and electrically connected with the electric signal control end of each optical signal delayer and the electric signal control end of each optical phase modulator.
2. The system of claim 1, wherein the optical signal retarder is a fiber tunable true retarder or a true delay module based on slow light effect.
3. The system of claim 1, wherein the optical signal phase modulator is a waveguide-based electro-optic modulator or a PZT-based electrically controlled piezoelectric ceramic true delay phase controller.
4. The system of claim 1, wherein said optical filter is a photonic crystal fiber filter.
5. The system of claim 1, wherein the output of said optical filter is coupled to an EDFA amplifier via an optical fiber or waveguide; the EDFA is connected with the input end of the photoelectric detector through an optical fiber or a waveguide.
6. A receiving system signal receiving method in wireless optical communication comprises the following steps:
1) focusing the spatial light signal by using a group of focusing lenses and feeding the spatial light signal into an optical fiber or waveguide array;
2) each path of the optical fiber or the waveguide array is subjected to phase delay through an optical signal delayer respectively;
3) respectively carrying out phase modulation on each path of phase-delayed signals by an optical signal phase modulator, and then coupling and outputting the signals into a path of optical signals;
4) filtering the processed optical signals, converting the filtered optical signals into electric signals, and outputting the electric signals to a decoding sampling judgment module and an analysis calculation control module respectively;
5) in a communication time slot, the decoding sampling judgment module recovers original information from a received electric signal;
6) and in a reference time slot, the analysis calculation control module performs feedback adjustment on the optical signal delayer and the optical signal phase modulator.
7. The method of claim 6, wherein the analysis calculation control module performs feedback adjustment on the optical signal delay and the optical signal phase modulator by using the average amplitude of the received electrical signals as a target variable and using the control electrical signals of the optical signal delay and the optical signal phase modulator in each path as a control variable.
8. The method of claim 6 or 7, wherein the output of the optical signal delay is connected to the input of the optical signal phase modulator by a waveguide or an optical fiber; the output end of each optical signal phase modulator is connected with one input end of the same coupler through a waveguide or an optical fiber.
9. The method of claim 8, wherein the filtering is performed using an optical filter connected to the output of the coupler by a waveguide or an optical fiber; the output end of the optical filter is connected with the input end of a photoelectric detector through a waveguide or an optical fiber to convert an optical signal into an electric signal.
10. The method of claim 6 or 7, wherein said optical signal delay and said optical signal phase modulator are feedback adjusted using a nested neighborhood optimization algorithm; the neighborhood optimization algorithm is a climbing algorithm or a simulated annealing algorithm.
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| CN102142896A (en) * | 2011-03-23 | 2011-08-03 | 北京大学 | Wide-angle lens and atomic filter-based optical signal detection system |
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