System and method for real-time recovery of high-speed long-haul communication signals using photon correlation

Abstract

The application discloses a system and method for real-time recovery of high-speed long-distance communication signals by using photon correlation, comprising an optical transmitter, an arbitrary waveform signal generator, a 100-kilometer optical fiber, an optical receiver and a signal storage device; the optical transmitter and the optical receiver are connected by two paths, one of which is connected through the 100-kilometer optical fiber, and the other is connected through a cable; the arbitrary waveform signal generator and the optical transmitter are connected through the cable, and the signal storage device and the optical receiver are also connected through the cable; the application adopts the photon correlation technology, has good tolerance for the inter-symbol interference caused by dispersion of a communication carrier, and does not need an optical repeater, thereby reducing the photo-electric-optical conversion process of the optical repeater, greatly improving the communication distance and efficiency; the photon correlation technology has low requirements for the detection bandwidth of the communication carrier, and solves the problem of limited bandwidth of high-speed signals.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of remote optical fiber communication, and particularly relates to a system and method for real-time recovery of high-speed remote communication signals by utilizing photon correlation. BACKGROUND

[0002] At present, the rapid increase in the number of communication users has put forward higher requirements for the realization of large-capacity high-speed signal transmission. Remote optical fiber communication often needs multiple optical repeaters. Affected by the slow response of electronic equipment, the "electronic bottleneck" may be encountered, and the bandwidth of the detector has a higher requirement. The transmission of signals is often accompanied by a high bit error rate, and signal eavesdropping is also relatively easy. These problems limit the distance, capacity, rate and security of communication, so the classical optical communication scheme needs to be improved.

[0003] Correlation measurement is widely used in the field of photon statistical characteristics. Based on correlation measurement, spatial two-photon imaging technology has emerged. By utilizing the time-space duality of light waves, spatial imaging can be extended to the time domain, i.e. photon correlation technology for signal transmission, which is a signal transmission method with high application prospect. In 2010, Shirai et al. theoretically proved the feasibility of time-domain photon correlation signal recovery of classical non-stationary light sources. In 2012, Cho et al. theoretically proposed a quantum light source time-domain signal recovery scheme. In 2013, Chen et al. verified the feasibility of time-domain photon correlation signal recovery through numerical simulation.

[0004] The existing remote optical fiber communication method and device have the problems of inter-symbol interference caused by fiber dispersion, signal distortion caused by inter-symbol interference and remote transmission loss between multiple optical repeaters, low transmission efficiency, high cost and the like, and new devices and methods are needed to improve the signal transmission efficiency and fidelity. SUMMARY

[0005] The purpose of the present application is to provide a system and method for real-time recovery of high-speed remote communication signals by utilizing photon correlation, so as to solve the problems existing in the prior art.

[0006] To achieve the above purpose, on the one hand, the present application provides a system for real-time recovery of high-speed remote communication signals by utilizing photon correlation, comprising:

[0007] The system comprises an optical transmitter, an arbitrary waveform signal generator, a 100-kilometer optical fiber, an optical receiver, and a signal memory. The optical transmitter and receiver are connected by two connections: one via the 100-kilometer optical fiber, and the other via a cable. The arbitrary waveform signal generator is connected to the optical transmitter via a cable, and the signal memory is connected to the optical receiver via a cable. The arbitrary waveform signal generator can generate arbitrary waveform electrical signals that are applied to a Mach-Zehnder modulator, including square waves, triangular waves, sine waves, etc., with a frequency range of 50MHz to 3GHz.

[0008] Optionally, the system also includes: an optical attenuation and dispersion control system, used to simulate the harsh communication environment during optical fiber communication;

[0009] The optical attenuation and dispersion control system includes an adjustable optical attenuator and a dispersion device;

[0010] The adjustable optical attenuator is model VOA-W1550-1-9-S15A, and the dispersion device is a TeraXion DMR series fiber dispersion manager.

[0011] Furthermore, the optical transmitter includes: a broadband noise source, a variable fiber beam splitter, a Mach-Zehnder modulator, and a high-speed photodetector;

[0012] The variable fiber beam splitter can change its splitting ratio arbitrarily under the drive of an external driving signal, and can achieve the required splitting ratio more accurately.

[0013] The Mach-Zehnder modulator can stably maintain its operating point state under the action of bias voltage, avoiding phase shift caused by temperature factors.

[0014] The high-speed photodetector can be selected with a bandwidth range of 1 GHz or higher, depending on the requirements.

[0015] Furthermore, the broadband noise source is capable of emitting light waves with random intensity fluctuations, which have inherent randomness over time and short coherence time. The broadband noise source is an ASE source, a chaotic source, or a thermal source.

[0016] The Mach-Zehnder modulator used is the iXblue MX-LN-10 series; the low-speed photodetector can be selected with a bandwidth of 10MHz or more as required, because the designed system is not sensitive to the time distortion of the communication carrier.

[0017] Furthermore, the optical receiver includes: a low-speed photodetector and a data acquisition and processing system;

[0018] The data acquisition and processing system is built on an FPGA and also includes an ADC module and a DAC module.

[0019] Furthermore, the system time resolution is affected by the coherence time of the broadband noise source, the response time of the high-speed photodetector and the ADC module in the data acquisition and processing system, and is determined by the larger of these factors.

[0020] On the other hand, the present invention provides a method for real-time recovery of high-speed long-distance communication signals using photon correlation, comprising the following steps:

[0021] S1. The optical transmitter transmits the electrical signal converted from the reference optical wave and the modulated communication carrier wave;

[0022] S2. The optical receiver receives the electrical signal converted from the reference optical wave and the modulated communication carrier wave;

[0023] S3. The optical receiver processes and recovers the electrical signal and the modulated communication carrier;

[0024] S4. Convert the recovered electrical signal into an analog transmission signal and send it to the signal memory.

[0025] Furthermore, S1 specifically involves: generating a light wave from a broadband noise source, splitting the light wave into two identical beams by a variable fiber beam splitter, which serve as the reference light wave and the communication carrier, respectively; measuring the reference light wave by a high-speed photodetector and converting it into an electrical signal; and using a transmission electrical signal generated by an arbitrary waveform signal generator to drive a Mach-Zehnder modulator to modulate the communication carrier.

[0026] The optical path length from the broadband noise source to the high-speed photodetector is the same as the optical path length to the Mach-Zehnder modulator. Then, the optical transmitter transmits the electrical signal converted from the reference light wave and the modulated communication carrier.

[0027] Furthermore, in S2: the electrical signal converted from the reference light wave is transmitted to the optical receiver via a cable, and the modulated communication carrier is transmitted to the optical receiver via a 100-kilometer optical fiber and an optical attenuation and dispersion control system.

[0028] Furthermore, S3 specifically involves: the low-speed photodetector in the optical receiver measuring the received modulated communication carrier, converting the optical signal into a communication carrier electrical signal, and the data acquisition and processing system performing high-speed acquisition and processing of the reference optical wave electrical signal and the communication carrier electrical signal. The ADC module realizes synchronous sampling and quantization of the two sets of electrical signal data, and the FPGA performs computational processing to obtain the recovered signal.

[0029] Furthermore, the specific processing procedure is as follows: Both sets of data are divided into T-row, n-column data matrices, where T represents the time rows and n represents the number of measurement points. Then, the average value of each measurement is taken to obtain an average signal measurement value. The average value of each of the two data matrices is then subtracted from the average value of the two matrices, multiplied, and finally normalized to obtain the correlated and recovered transmission signal. The DAC performs digital-to-analog conversion on the data processed by the FPGA, outputting an analog transmission signal.

[0030] The technical effects of this invention are as follows:

[0031] (1) This invention uses photonic correlation technology for ultra-long-distance signal transmission, with an effective transmission distance of over 320km. It does not require optical repeaters, reducing the optical-electrical-optical conversion process of optical repeaters, greatly improving communication distance and efficiency, and realizing efficient inter-city ultra-long-distance communication.

[0032] (2) The method described in this invention achieves high-fidelity transmission of high-speed signals. Optical attenuation and dispersion control simulate harsh communication environments. By utilizing photonic correlation technology, the communication carrier has good tolerance to inter-symbol interference caused by dispersion. It completes ultra-long-distance transmission of random sequences above 2Gb / s with 65dB attenuation. Compared with traditional communication methods, the signal fidelity is improved by two orders of magnitude, demonstrating the system's strong robustness and anti-fading ability.

[0033] (3) The method described in this invention solves the problem of limited bandwidth for high-speed signals. Traditional communication detection is limited by the Nyquist theorem. High-speed communication carriers require high-bandwidth detectors to receive them. Photon correlation technology has low requirements for the detection bandwidth of the communication carrier and enables the recovery of random sequences with a transmission rate of 2Gb / s or higher by a 200MHz detector. Attached Figure Description

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0035] Figure 1 This is a schematic diagram of the device structure in an embodiment of the present invention, wherein solid lines represent optical fiber connections and dashed lines represent cable connections;

[0036] Figure 2 A time fluctuation diagram of the output intensity of the reference light wave emitted by the ASE light source in the embodiment of the present invention;

[0037] Figure 3 The 2Gb / s transmission electrical signal is generated by the arbitrary waveform signal generator in the embodiments of the present invention.

[0038] Figure 4This is a comparison diagram of the transmission signal, the photon correlation recovery signal, and the signal recovered by the conventional method in this embodiment of the invention;

[0039] Figure 5 The graph shows the variation of the mean square error (MSE) of the photon correlation recovery signal and the conventional recovery signal in the embodiment of the present invention.

[0040] In the diagram: 1-Optical transmitter; 2-Broadband noise source; 3-Variable fiber beam splitter; 4-Mach-Zehnder modulator; 5-Arbitrary waveform signal generator; 6-High-speed photodetector (bandwidth above 1GHz); 7-Hundred-kilometer fiber optic cable; 8-Optical attenuation and dispersion control system; 9-Adjustable optical attenuator; 10-Dispersion device; 11-Optical receiver; 12-Low-speed photodetector (bandwidth above 10MHz); 13-Data acquisition and processing system; 14-Signal memory. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Example 1

[0043] like Figures 1-5 As shown, in order to solve the problems of signal distortion caused by inter-symbol interference and low transmission efficiency caused by setting up optical repeaters in existing optical fiber communication, this embodiment provides a system and method for real-time recovery of high-speed remote communication signals using photon correlation.

[0044] like Figure 1 As shown, this embodiment of the invention provides a system for real-time recovery of high-speed long-distance communication signals using photon correlation, including an optical transmitter 1, an arbitrary waveform signal generator 5, a 100-kilometer optical fiber 7, an optical attenuation and dispersion control system 8, an optical receiver 11, and a signal memory 14.

[0045] The optical transmitter 1 includes a broadband noise source 2, a variable fiber beam splitter 3, a Mach-Zehnder modulator 4, and a high-speed photodetector 6. The arbitrary waveform signal generator 5 generates a transmission signal, which is input to the Mach-Zehnder modulator 4 to modulate the communication carrier. The broadband noise source 2 generates light waves that are incident on the variable fiber beam splitter 3, splitting them into two identical beams, which serve as a reference light wave and the communication carrier, respectively. The reference light wave is measured by the high-speed photodetector 6 and transmitted to the optical receiver 11. The communication carrier is modulated by the Mach-Zehnder modulator 4, which is generated by the arbitrary waveform signal generator 5. Driven by an electrical signal, the modulated light wave passes through a 100-kilometer optical fiber 7, and then through an optical attenuation and dispersion control system 8 composed of an adjustable optical attenuator 9 and a dispersion device 10 for communication transmission. After the light wave modulated by the applied transmission signal passes through the 100-kilometer optical fiber 7 and the optical attenuation and dispersion control system 8, it is transmitted to an optical receiver 11 and measured by a low-speed photodetector 12. The data acquisition and processing system 13 is mainly composed of an FPGA and also includes an ADC module and a DAC module to realize the acquisition and processing of the output data of the high-speed photodetector 6 and the low-speed photodetector 12. Finally, the recovered transmission signal is sent to the signal memory 14.

[0046] Specifically, in this embodiment, the broadband noise source 2 adopts an OS8143 series desktop ASE light source, which can emit light waves with random intensity fluctuations. These fluctuations over time have inherent randomness; when the light field intensity fluctuates in time and space, the intensity distribution differs with each measurement, and the total light intensity interacting with the transmitted signal changes. Therefore, each measurement can obtain partial information about the signal. The coherence time of the light source is 0.2 ps.

[0047] Specifically, in this embodiment, the variable fiber beam splitter 3 is an Agiltron NSVS-12-5-5-1-1-3-3-3 model, whose beam splitting ratio can be precisely changed with the external driving signal, making the splitting of the beam more controllable and accurate.

[0048] Specifically, in this embodiment, the arbitrary waveform signal generator 5 uses a bit error rate meter to generate a 2Gb / s random sequence; the high-speed photodetector 6 is a 50GHz high-speed detection module of the Finisar brand XPDV2120RA; the Mach-Zehnder modulator 4 is an iXblue MX-LN-10-PD-PP-FA-FA model; the low-speed photodetector 12 is a KG-APR-200M series APD photodetector module manufactured by Kangguan Optoelectronics; and the FPGA in the data acquisition and processing system 13 is a Xilinx Kintex-7 XC7K325T with an ADC bandwidth of 5GHz. Combining the coherence time of the ASE light source, the bandwidth of the high-speed photodetector, and the ADC, it can be determined that the detectable signal bandwidth of this system is 2.5GHz.

[0049] Specifically, in this embodiment, the adjustable optical attenuator 9 is model VOA-W1550-1-9-S15A, and the dispersion device 10 adopts TeraXion's DMR series fiber dispersion manager. The two constitute the optical attenuation and dispersion control system 8 to simulate the harsh communication environment in the process of optical fiber communication.

[0050] like Figure 2 The figure shown is a time fluctuation diagram of the output intensity of the reference light wave emitted by the ASE light source in an embodiment of the present invention; as shown Figure 3 The figure shows a 2Gb / s transmission electrical signal generated by an arbitrary waveform signal generator in an embodiment of the present invention;

[0051] Figure 4 This is a comparison diagram of three signals in this embodiment of the invention. For ease of comparison, only the signal timing diagram of the first 5 ns is shown here. Due to attenuation and dispersion during transmission, inter-symbol interference occurs, causing distortion of the signal detected by traditional methods. However, the recovered signal obtained by the photon correlation method has significant consistency with the original transmitted signal sequence. Specifically, it accurately reproduces the original transmitted signal in terms of duration and amplitude. The mean square error of the transmitted signal recovered by the photon correlation method is 1.01 × 10^(-3), while the mean square error of the transmitted signal obtained by traditional measurement is 2.14 × 10^(-1), an improvement of two orders of magnitude.

[0052] Figure 5 This figure shows the mean square error (MSE) changes of the photon correlation-recovered signal and the conventionally recovered signal, respectively, in this embodiment of the invention. The figure clearly demonstrates that our system achieves high signal fidelity and good stability in the recovered signal.

[0053] This invention also provides a method for real-time recovery of high-speed long-distance communication signals using photon correlation, comprising the following steps:

[0054] (I) Optical transmitter transmits signals: Broadband noise light source 2 generates reference light wave and communication carrier, arbitrary waveform signal generator 5 generates transmission electrical signal, and optical transmitter 1 transmits reference light wave and modulated communication carrier.

[0055] Furthermore, the light wave generated by the broadband noise source 2 is precisely split into two identical beams by the variable fiber beam splitter 3, which serve as a reference light wave and a communication carrier wave, respectively. The reference light wave is directly measured by the high-speed photodetector 6, which records the intensity fluctuations of the light source over time and converts the reference light wave into an electrical signal. The Mach-Zehnder modulator 4 is driven by the transmission electrical signal generated by the arbitrary waveform signal generator 5 to modulate the communication carrier wave. The electrical signal converted from the reference light wave and the modulated communication carrier wave are then transmitted by the optical transmitter 1.

[0056] (ii) The modulated communication carrier passes through a hundred-kilometer optical fiber 7 and an optical attenuation and dispersion control system 8 for optical fiber communication.

[0057] (iii) The reference optical wave electrical signal and the communication carrier after optical fiber communication are received by the optical receiver 11, and the signal is acquired and processed by the optical receiver.

[0058] Furthermore, in the optical receiver 11, the low-speed photodetector 12 is used to measure the communication carrier, converting the optical signal into an electrical signal. The data acquisition and processing system 13 is used for high-speed acquisition and processing of the reference optical wave electrical signal and the communication carrier electrical signal. The ADC module synchronously samples and quantizes the two sets of electrical signal data, while the FPGA performs the data processing. Specifically, the two sets of data are divided into T-row, n-column data matrices, where T represents the time rows and n represents the number of measurement points. The average value of each measurement is then calculated, and the average value of each data matrix is ​​subtracted from the average value of the two data matrices, multiplied, and finally normalized to obtain the correlated and recovered transmission signal. The DAC performs digital-to-analog conversion on the data processed by the FPGA, outputting an analog transmission signal.

[0059] The mathematical expression corresponding to this operation is:

[0060]

[0061] Where R(t) is the transmission signal recovered from photon correlation. R (t) represents the collected reference optical wave electrical signal data, S C (t) represents the collected communication carrier electrical signal data. The average of the measured data for each group is then calculated, with the sign... This indicates calculating the mean. This represents the average value of the reference electrical signal data. The mean of the communication carrier electrical signal data is represented. The mean of each of the two data matrices is subtracted, multiplied, and then normalized to obtain the correlated and recovered transmission signal. T represents the duration of the acquired signal. The DAC performs digital-to-analog conversion on the data processed by the FPGA and outputs the analog transmission signal to the signal storage.

[0062] (iv) The finally recovered transmission signal is sent to the signal memory 14. That is... Figure 4 The transmitted signal recovered by the photon correlation method is presented.

[0063] This invention utilizes photonic correlation technology for real-time signal recovery, solving problems such as signal distortion caused by intersymbol interference and low transmission efficiency caused by optical repeaters in existing optical fiber communication. It can be widely used in fields such as real-time signal transmission and long-distance optical fiber communication in harsh environments.

[0064] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for real-time recovery of high-speed long-distance communication signals using photon correlation, characterized in that, Includes the following steps: S1. The optical transmitter transmits the electrical signal converted from the reference optical wave and the modulated communication carrier wave; S2. The optical receiver receives the electrical signal converted from the reference optical wave and the modulated communication carrier wave; S3. The optical receiver processes and recovers the electrical signal and the modulated communication carrier; S4. Convert the recovered electrical signal into an analog transmission signal and send it to the signal memory; S1 specifically involves: generating a light wave from a broadband noise source; splitting the light wave into two identical beams by a variable fiber beam splitter, which serve as the reference light wave and the communication carrier, respectively; measuring the reference light wave by a high-speed photodetector and converting it into an electrical signal; and using a transmission electrical signal generated by an arbitrary waveform signal generator to drive a Mach-Zehnder modulator to modulate the communication carrier. The optical path length from the broadband noise source to the high-speed photodetector is the same as the optical path length to the Mach-Zehnder modulator. Then, the optical transmitter transmits the electrical signal converted from the reference light wave and the modulated communication carrier. S3 specifically involves: the low-speed photodetector in the optical receiver measuring the received modulated communication carrier and converting the optical signal into a communication carrier electrical signal; the data acquisition and processing system performing high-speed acquisition and processing of the reference optical wave electrical signal and the communication carrier electrical signal; wherein the ADC module realizes synchronous sampling and quantization of the two sets of electrical signal data; and the FPGA performs computational processing to obtain the recovered signal. The specific process of the operation is as follows: divide both sets of data into T rows and n columns of data matrix, where T represents the time row and n represents the number of measurement points; then take the average value of each measurement result to obtain an average value of signal measurement; then subtract the average value of each of the two sets of data matrices and multiply them; finally, perform normalization calculation to obtain the correlated recovered transmission signal; the DAC realizes the digital-to-analog conversion of the data processed by the FPGA and outputs the analog transmission signal.

2. The method according to claim 1, characterized in that, In S2: the electrical signal converted from the reference light wave is transmitted to the optical receiver via a cable, and the modulated communication carrier is transmitted to the optical receiver via a 100-kilometer optical fiber and an optical attenuation and dispersion control system.

3. A system for real-time recovery of high-speed long-distance communication signals using photon correlation, the system being used to perform the method according to any one of claims 1-2, characterized in that, include: Optical transmitter, arbitrary waveform signal generator, 100-kilometer optical fiber, optical receiver, signal memory; The optical transmitter and the optical receiver are connected by two connections: one is through the 100-kilometer optical fiber, and the other is through a cable. The arbitrary waveform signal generator is connected to the optical transmitter through a cable, and the signal memory is connected to the optical receiver through a cable.

4. The system according to claim 3, characterized in that, Also includes: Optical attenuation and dispersion control system, used to simulate the harsh communication environment in optical fiber communication process; The light attenuation and dispersion control system includes an adjustable light attenuator and a dispersion device.

5. The system according to claim 4, characterized in that, The optical transmitter includes: a broadband noise source, a variable fiber beam splitter, a Mach-Zehnder modulator, and a high-speed photodetector; The variable fiber beam splitter can change its splitting ratio arbitrarily under the drive of an external driving signal, and can accurately achieve the required splitting ratio. The Mach-Zehnder modulator can stably maintain its operating point state under the action of bias voltage, avoiding phase shift caused by temperature factors. The bandwidth of the high-speed photodetector is above 1 GHz.

6. The system according to claim 5, characterized in that, The broadband noise source is an ASE source, a chaotic source, or a thermal source.

7. The system according to claim 3, characterized in that, The optical receiver includes: a low-speed photodetector and a data acquisition and processing system; The data acquisition and processing system is built on an FPGA and also includes an ADC module and a DAC module; The bandwidth of the low-speed photodetector is above 10MHz.

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