Optical forward error correction encoding method and apparatus based on matrix multiplication

Abstract

The application provides an optical forward error correction coding method and device based on matrix multiplication, comprising a narrowband laser, a radio frequency signal generator, a multiplier, an electro-optic intensity modulator, an optical frequency comb, a photoelectric detector and a low-pass filter; the electro-optic intensity modulator is used to realize an electrical-optical conversion process of a coding signal, then each row of coding information is stored in a corresponding frequency optical signal of the optical frequency comb, after optical fiber transmission, the photoelectric detector is used to accumulate and store information row by row at a receiving end, after the low-pass filter filters out redundant frequency signals, the final coding signal output is realized. The application effectively reduces the electronic devices required in the coding process and has strong anti-electromagnetic interference ability; the memory device based on the optical frequency comb can effectively reduce the number of times of accessing the electrical memory device in the coding process and reduce transmission loss; meanwhile, the application has high integration and high degree of freedom with the optical fiber system, and finally the encoder based on the application can fully utilize the high bandwidth and low time delay advantages of the optical signal.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and more specifically, to an optical forward error correction coding method and apparatus based on matrix multiplication. Background Technology

[0002] With the rapid increase in demand for communication speed and information accuracy in modern society, industry and researchers have been continuously focusing on the development of higher-performance communication systems. Specifically, higher-performance communication systems mean higher communication speeds, larger communication bandwidths, and higher information accuracy. Forward error correction coding (FEC) is a technique for detecting and correcting erroneous bits during information transmission. This technique sacrifices some channel bandwidth to add redundant parity bits, reducing the impact of channel noise on transmitted information, thereby effectively reducing the bit error rate. Good coding schemes are closer to the theoretical Shannon limit and possess superior error correction performance; therefore, achieving coding and decoding schemes close to the theoretical limit has always been a hot research topic. Currently commonly used channel coding techniques include Reed-Solomon codes, Turbo codes, and low-density parity check codes (LDPC).

[0003] Currently, mainstream encoder physical devices are based on integrated electronic devices, such as large-scale integrated circuits (LSI), application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). Thanks to highly mature microelectronics manufacturing processes, these integrated electronic devices possess characteristics of high integration, high speed, and specialized function. However, as Moore's Law gradually approaches its limits, the performance of integrated circuits is approaching theoretical bottlenecks: high-density electronic device distribution leads to enhanced electromagnetic interference, causing increased losses, increased heat dissipation requirements, and a series of other problems. At the same time, highly specialized functions sacrifice some user freedom. Finally, electrical encoders require a modulator to convert electrical signals into optical signals before they can be loaded onto optical fibers for signal transmission, and the frequent access to electrical memory and other operations involved further increase system power consumption.

[0004] Therefore, in order to solve the above-mentioned problems, it is necessary to develop an optical forward error correction coding method and device based on matrix multiplication to realize a more flexible and lower power consumption encoder. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an optical forward error correction coding method and apparatus based on matrix multiplication.

[0006] An optical forward error correction coding device based on matrix multiplication according to the present invention includes: a narrowband laser, a generator matrix radio frequency signal generator, a transmission signal radio frequency signal generator, a multiplier, an electro-optic intensity modulator, an optical frequency comb generation system, a photodetector, and a low-pass filter;

[0007] The output terminals of the generator matrix RF signal generator and the transmission signal RF signal generator are electrically connected to the input terminal of the multiplier, respectively. The output terminal of the multiplier is electrically connected to the input terminal of the electro-optic intensity modulator. The output terminal of the narrowband laser is optically connected to the input terminal of the electro-optic intensity modulator, and the output terminal of the electro-optic intensity modulator is optically connected to the input terminal of the optical frequency comb generation system. The output terminal of the optical frequency comb generation system is optically connected to the input terminal of the photodetector, and the output terminal of the photodetector is electrically connected to the input terminal of the low-pass filter.

[0008] Preferably, the optical frequency comb generation system includes: a polarization controller, a 1:1 2×2 coupler, an electro-optic IQ modulator, a sinusoidal signal radio frequency signal generator, an erbium-doped fiber amplifier, and an optical bandpass filter;

[0009] The output of the electro-optic intensity modulator is optically connected to the input of the polarization controller. The output of the polarization controller is optically connected to the first input of the 1:1 2×2 coupler. The second output of the 1:1 2×2 coupler, the electro-optic IQ modulator, the erbium-doped fiber amplifier, the optical bandpass filter, and the second input of the 1:1 2×2 coupler are sequentially optically connected to form a loop. The output of the sinusoidal signal RF generator is electrically connected to the input of the electro-optic IQ modulator. The first output of the 1:1 2×2 coupler is optically connected to the input of the photodetector.

[0010] Preferably, the electro-optic IQ modulator achieves carrier-suppressed single-sideband modulation by adjusting the bias voltage.

[0011] Preferably, the 1:1 2×2 coupler can be replaced with a coupler with a splitting ratio of 30:70 or 10:90 to ensure that the optical power at the second output end is not less than the optical power at the first output end and the optical power at the second input end is not less than the optical power at the first input end.

[0012] According to the optical forward error correction coding method based on matrix multiplication provided by the present invention, the following steps are performed using the aforementioned optical forward error correction coding device based on matrix multiplication:

[0013] Step S1: Multiply the two signals generated by the generator matrix RF signal generator and the transmission signal RF signal generator through a multiplier to generate an electrical signal;

[0014] Step S2: Output the electrical signal from the multiplier to the electro-optic intensity modulator to achieve electro-optic signal conversion;

[0015] Step S3: Store the optical signal output by the electro-optic intensity modulator in the optical signal of the corresponding frequency of the optical frequency comb based on the optical frequency comb generation system;

[0016] Step S4: Input the signal output from the optical frequency comb generation system into the photodetector to obtain an electrical signal;

[0017] Step S5: The electrical signal is input to a low-pass filter to remove redundant frequencies, and then the final encoded signal is obtained.

[0018] Preferably, step S1 employs:

[0019] During the loop time [iτ, (i+1)τ), the generator matrix RF signal generator sends the i-th row (i = 1, 2, ..., M) signal, with each bit signal lasting for a duration of [iτ, (i+1)τ]. Time, where M is the number of rows in the generator matrix, τ is the time delay of one loop, and K is the number of columns in the generator matrix, and the generator matrix corresponds to an M×K matrix;

[0020]

[0021] The radio frequency signal generator transmits the i-th signal within the time interval [iτ, (i+1)τ), where i = 1, 2, ..., M; M is the length of the transmitted signal;

[0022] s = [a1, a2, ..., a M ]

[0023] Among them, a i b represents the i-th element of the transmitted signal s; ij This represents the element in the i-th row and j-th column of the generating matrix G;

[0024] The electrical signals generated by the multiplier include:

[0025] s i =[a i b i1 a i b i2 , ..., a i b iK ],t∈[iτ,(i+1)τ).

[0026] Preferably, step S2 involves: within the time interval [iτ, (i+1)τ), the intensity of the input optical signal of the narrowband laser is E0, and the intensity of the output optical signal of the electro-optic intensity modulator is... Among them, V π1 It is the half-wave voltage of the electro-optic intensity modulator; s i This represents the electrical signal output by the multiplier at time [iτ, (i+1)τ).

[0027] Preferably, step S3 uses the following output signal form of the first output terminal of a 1:1 2×2 coupler, the specific form of which depends on whether the carrier suppression single sideband retains the positive first-order sideband or the negative first-order sideband;

[0028] When the positive first-order sideband is retained, the output signal is in the form of E. OFC1 When the negative first-order sideband is retained, the output signal is in the form of E. OFC2 :

[0029]

[0030] Among them, E OFC1 E represents the total output signal intensity of a 2×2 coupler with a 1:1 ratio under positive first-order carrier-suppressed single-sideband modulation after M cycles; OFC2 This represents the total output signal intensity of a 2×2 coupler with a 1:1 ratio under negative first-order carrier-suppressed single-sideband modulation after M cycles; s m J represents the output electrical signal of the multiplier in the m-th cycle. ±1 (x) is the corresponding Bessel function, V pp It is the peak voltage of the sinusoidal signal output by the sinusoidal signal RF signal generator, V. π2 V represents the sub-modulator half-wave voltage of the electro-optic IQ modulator. bias It is the DC bias voltage of the electro-optic IQ modulator; f0 represents the frequency of the single-wavelength optical signal output by the narrowband laser. c This indicates the frequency of the sinusoidal signal output by the RF signal generator. This indicates the additional phase introduced by the optical signal as it circulates in the loop.

[0031] Preferably, the optical frequency comb generation system needs to ensure that the bandwidth meets the condition: Nf c ≤B<(N+1)f c Where N is the number of comb teeth required, which is an integer multiple of the length of the encoded signal; f c It is the frequency interval of the optical frequency comb signal.

[0032] Preferably, the photodetector converts the signal output by the optical frequency comb generation system into an electrical signal;

[0033] In the process of converting optical signals into electrical signals, the photodetector adds the information stored in the optical frequency comb teeth to achieve the addition of each row of the matrix.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention realizes an encoder that partially replaces the electronic memory by using a storage system based on optical fiber devices, achieving the effects of integrated transmission and storage and homomorphic transmission of optical signals. This reduces the number of electro-optical conversion steps and electrical storage memory access operations, thereby reducing power loss, computation delay and electromagnetic interference.

[0036] 2. By primarily employing optical devices, represented by optical fibers, this invention achieves good compatibility with existing optical fiber communication systems, while also being low in manufacturing cost and exhibiting stable performance.

[0037] 3. By allowing users to adjust the number of teeth on the optical frequency comb, this invention achieves the technical effect of dynamically adjusting the optical storage length, which has greater flexibility and freedom compared to traditional dedicated encoders.

[0038] 4. By utilizing the technical characteristics of optical signals such as large bandwidth, low latency, and low loss, this invention achieves potential technical effects such as good parallelism, low error, and high speed.

[0039] 5. By utilizing the multi-wavelength technology characteristics of optical signals, this invention enables multiple encoders to work simultaneously in different bands, thereby improving system parallelism, achieving parallel coding tasks, and further accelerating coding speed. Attached Figure Description

[0040] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0041] Figure 1 This is a schematic diagram of an optical forward error correction coding method based on matrix multiplication.

[0042] Figure 2 This is a schematic diagram of an embodiment of an optical forward error correction coding device based on matrix multiplication.

[0043] Figure 3 This is a schematic diagram of the simulation results of a positive first-order carrier-suppressed single-sideband modulation when the extinction ratio of the electro-optic IQ modulator sub-modulator is 30dB.

[0044] Figure 4 This is a simulation example of an optical frequency comb generation scheme based on a cyclic frequency shifting system.

[0045] Figure 5 It refers to the encoder's corresponding output results under different input data.

[0046] Figure 6 This is a comparison of the bit error rate-signal-noise ratio curves of the encoder simulation example of this invention, the encoder simulation example implemented in MATLAB, and the on-off keying (OOK) digital modulation without FEC.

[0047] Among them, 100-electrical connection, 110-optical connection, 120-narrowband laser, 130-generating matrix RF signal generator, 140-transmitting signal RF signal generator, 150-multiplier, 160-electro-optic intensity modulator, 170-optical frequency comb generation system, 180-photodetector, 190-low-pass filter.

[0048] 2000 - Electrical connection, 2010 - Optical connection, 2020 - Narrowband laser, 2030 - Generator matrix RF signal generator, 2040 - Transmit signal RF signal generator, 2050 - Multiplier, 2060 - Electro-optic intensity modulator, 2070 - Polarization controller, 2080 - 1:1 2×2 coupler, 2090 - Sine wave signal RF signal generator, 2100 - Electro-optic IQ modulator, 2110 - Erbium-doped fiber amplifier, 2120 - Optical bandpass filter, 2130 - Photodetector, 2140 - Low-pass filter. Detailed Implementation

[0049] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0050] The purpose of this invention is to provide an optical forward error correction coding method and apparatus based on matrix multiplication, which fully utilizes the advantages of high speed, large bandwidth and low electromagnetic interference of optical signals, has high compatibility with existing optical fiber systems, and provides users with adjustment freedom.

[0051] Example 1

[0052] An optical forward error correction coding device based on matrix multiplication according to the present invention includes: a narrowband laser, a generator matrix radio frequency signal generator, a transmission signal radio frequency signal generator, a multiplier, an electro-optic intensity modulator, an optical frequency comb generation system, a photodetector, and a low-pass filter;

[0053] The output terminals of the generator matrix RF signal generator and the transmission signal RF signal generator are electrically connected to the input terminal of the multiplier, respectively. The output terminal of the multiplier is electrically connected to the input terminal of the electro-optic intensity modulator. The output terminal of the narrowband laser is optically connected to the input terminal of the electro-optic intensity modulator, and the output terminal of the electro-optic intensity modulator is optically connected to the input terminal of the optical frequency comb generation system. The output terminal of the optical frequency comb generation system is optically connected to the input terminal of the photodetector, and the output terminal of the photodetector is electrically connected to the input terminal of the low-pass filter.

[0054] Specifically, the signal rate at the output of the multiplier is not greater than the interval frequency of the optical frequency comb.

[0055] Specifically, the narrowband laser is activated by injecting an initial optical signal into the matrix multiplication-based optical forward error correction coding device, and the device is kept running by continuously inputting an optical signal.

[0056] Specifically, the electro-optic intensity modulator is based on a Mach-Zehnder intensity modulator and is used to load the output electrical signal of the multiplier onto the output optical signal of the narrowband laser, so that the intensity of the output optical signal is proportional to the amplitude of the electrical signal.

[0057] Specifically, the optical frequency comb generation system includes: a polarization controller, a 1:1 2×2 coupler, an electro-optic IQ modulator, a sinusoidal signal radio frequency signal generator, an erbium-doped fiber amplifier, and an optical bandpass filter;

[0058] The output of the electro-optic intensity modulator is optically connected to the input of the polarization controller. The output of the polarization controller is optically connected to the first input of the 1:1 2×2 coupler. The second output of the 1:1 2×2 coupler, the electro-optic IQ modulator, the erbium-doped fiber amplifier, the optical bandpass filter, and the second input of the 1:1 2×2 coupler are sequentially optically connected to form a loop. The output of the sinusoidal signal RF generator is electrically connected to the input of the electro-optic IQ modulator. The first output of the 1:1 2×2 coupler is optically connected to the input of the photodetector.

[0059] Specifically, the electro-optic IQ modulator achieves carrier-suppressed single-sideband modulation by adjusting the bias voltage.

[0060] Specifically, the 1:1 2×2 coupler can be replaced with couplers with a splitting ratio of 30:70 or 10:90 to ensure that the optical power at the second output end is not less than the optical power at the first output end and the optical power at the second input end is not less than the optical power at the first input end.

[0061] The erbium-doped fiber amplifier is used to amplify the optical signal in the loop and compensate for the noise loss introduced by the loop; the optical bandpass filter is used to limit the number of optical frequency comb signals and mitigate the noise accumulation effect, providing system degrees of freedom.

[0062] The bandwidth of the low-pass filter is equal to the frequency of the signal at the output of the multiplier. Other bandwidth settings require technicians to adjust parameters such as the signal sampling frequency at the same time.

[0063] According to the optical forward error correction coding method based on matrix multiplication provided by the present invention, the following steps are performed using the aforementioned optical forward error correction coding device based on matrix multiplication:

[0064] Step S1: Multiply the two signals generated by the generator matrix RF signal generator and the transmission signal RF signal generator through a multiplier to generate an electrical signal;

[0065] Step S2: Output the electrical signal from the multiplier to the electro-optic intensity modulator to achieve electro-optic signal conversion;

[0066] Step S3: Store the optical signal output by the electro-optic intensity modulator in the optical signal of the corresponding frequency of the optical frequency comb based on the optical frequency comb generation system;

[0067] Step S4: Input the signal output from the optical frequency comb generation system into the photodetector to obtain an electrical signal;

[0068] Step S5: The electrical signal is input to a low-pass filter to remove redundant frequencies, and then the final encoded signal is obtained.

[0069] Specifically, step S1 employs the following:

[0070] During the loop time [iτ, (i+1)τ), the generator matrix RF signal generator sends the i-th row (i = 1, 2, ..., M) signal, and each bit signal lasts for a period of time. Time, where M is the number of rows in the generator matrix, τ is the time delay of one loop, and K is the number of columns in the generator matrix, and the generator matrix corresponds to an M×K matrix;

[0071]

[0072] The radio frequency signal generator transmits the i-th signal within the time interval [iτ, (i+1)τ), where i = 1, 2, ..., M; M is the length of the transmitted signal;

[0073] s = [a1, a2, ..., a M ]

[0074] Among them, a i b represents the i-th element of the transmitted signal s; ij This represents the element in the i-th row and j-th column of the generating matrix G;

[0075] The electrical signals generated by the multiplier include:

[0076] si =[a i b i1 a i b i2 , ..., a i b iK ],t∈[iτ,(i+1)τ).

[0077] Specifically, step S2 employs the following: within the time interval [iτ, (i+1)τ), the intensity of the input optical signal of the narrowband laser is E0, and the intensity of the output optical signal of the electro-optic intensity modulator is... Among them, V π1 It is the half-wave voltage of the electro-optic intensity modulator; s i This represents the electrical signal output by the multiplier at time [iτ, (i+1)τ).

[0078] Specifically, step S3 adopts the following output signal form of the first output terminal of the 1:1 2×2 coupler, the specific form of which depends on whether the carrier suppression single sideband retains the positive first-order sideband or the negative first-order sideband;

[0079] When the positive first-order sideband is retained, the output signal is in the form of E. OFC1 When the negative first-order sideband is retained, the output signal is in the form of E. OFC2 :

[0080]

[0081] Among them, E OFC1 E represents the total output signal intensity of a 2×2 coupler with a 1:1 ratio under positive first-order carrier-suppressed single-sideband modulation after M cycles; OFC2 This represents the total output signal intensity of a 2×2 coupler with a 1:1 ratio under negative first-order carrier-suppressed single-sideband modulation after M cycles; s m J represents the output electrical signal of the multiplier in the m-th cycle. ±1 (x) is the corresponding Bessel function, V pp It is the peak voltage of the sinusoidal signal output by the sinusoidal signal RF signal generator, V. π2 V represents the sub-modulator half-wave voltage of the electro-optic IQ modulator. bias It is the DC bias voltage of the electro-optic IQ modulator; f0 represents the frequency of the single-wavelength optical signal output by the narrowband laser. c This indicates the frequency of the sinusoidal signal output by the RF signal generator. This indicates the additional phase introduced by the optical signal as it circulates in the loop.

[0082] Specifically, the optical frequency comb generation system needs to ensure that the bandwidth meets the condition: Nf c ≤B<(N+1)f cWhere N is the number of comb teeth required, which is an integer multiple of the length of the encoded signal; f c This refers to the signal interval frequency of the optical frequency comb. For better encoding performance, the optical frequency comb needs to maintain a flatness of less than 5dB and a carrier signal-to-noise ratio of greater than 30dB.

[0083] Specifically, the photodetector converts the optical signal into an electrical signal, and the photodetector adds the information stored in the optical frequency comb teeth, which is equivalent to matrix inter-row addition, facilitating subsequent decoding processing.

[0084] Specifically, the optical frequency comb can be implemented using a discrete system based on fiber optic devices, such as a cyclic frequency shifting scheme with carrier-suppressed single-sideband; or it can be implemented using an on-chip integrated system, such as a Kerr optical comb.

[0085] Specifically, the low-pass filter filters out redundant signals and smooths the electrical signal curve. In a preferred embodiment of the present invention, the cutoff frequency of the low-pass filter is equal to the output signal rate of the multiplier.

[0086] The subsequent processing of the output encoded signal is implemented using mainstream electronic devices, including operations such as segmentation, amplification, quantization, and finite field transformation.

[0087] The encoding method is applicable to other matrix multiplication-based encoding methods within finite fields or integer fields, including but not limited to low-density parity check code generation matrix encoding method and low-density parity check code parity matrix encoding method.

[0088] Example 2

[0089] Example 2 is a preferred example of Example 1.

[0090] A preferred embodiment of the present invention is illustrated in the figure below. Figure 1-2As shown, this embodiment uses a cyclic frequency-shifting fiber discrete system to generate an optical frequency comb and implements a low-density parity-check code encoder in a finite field 2 based on an optical forward error correction coding method using matrix multiplication. According to the present invention, an optical forward error correction coding device based on matrix multiplication includes: a narrowband laser 2020, a generator matrix RF signal generator 2030, a transmission signal RF signal generator 2040, a multiplier 2050, an electro-optic intensity modulator 2060, a polarization controller 2070, a 1:1 2×2 coupler 2080, a sinusoidal signal RF generator 2090, an electro-optic IQ modulator 2100, an erbium-doped fiber amplifier 2110, an optical bandpass filter 2120, a photodetector 2130, and a low-pass filter 2140. The output terminals of the generator matrix RF signal generator 2030 and the transmission signal RF signal generator 2040 are electrically connected to the input terminal of the multiplier 2050, respectively. The output terminal of the multiplier 2050 is electrically connected to the input terminal of the electro-optic intensity modulator 2060. The output terminal of the narrowband laser 2020 is optically connected to the input terminal of the electro-optic intensity modulator 2060. The output terminal of the electro-optic intensity modulator 2060 is optically connected to the input terminal of the polarization controller 2070. The output terminal of the polarization controller 2070 is optically connected to the first input terminal of the 1:1 2×2 coupler 2080. The second output terminal of the 1:1 2×2 coupler 2080, the electro-optic IQ modulator 2100, the erbium-doped fiber amplifier 2110, the optical bandpass filter 2120, and the second input terminal of the 1:1 2×2 coupler 2080 are sequentially optically connected to form a loop. The output terminal of the sinusoidal signal RF generator 2090 is electrically connected to the input terminal of the electro-optic IQ modulator 2100. The first output terminal of the 1:1 2×2 coupler 2080 is optically connected to the input terminal of the photodetector 2130. The output terminal of the photodetector 2130 is electrically connected to the input terminal of the low-pass filter 2140. The output terminal of the low-pass filter 2140 is the encoding result output terminal of this invention.

[0091] The principle of the cyclic frequency shifting optical frequency comb generation scheme in this embodiment is as follows:

[0092] The electro-optic IQ modulator achieves carrier-suppressed single-sideband modulation. The sinusoidal signal RF generator 2090 generates two sinusoidal signals with equal frequency and amplitude but a 90° phase difference, which are input to the two electrical input terminals of the electro-optic IQ modulator 2100. Adjusting the bias voltage of the electro-optic IQ modulator 2100 changes the operating state of the sub-modulator, ultimately achieving high suppression ratio carrier-suppressed single-sideband modulation. The narrowband laser 2020 generates an optical carrier with frequency f0, and the RF signal generator generates a sinusoidal signal with frequency f... c The output signal of the electro-optic IQ modulator 2100 is f0 + f c or f0-fc The main interference frequencies are f0-3f. c or f0+3f c The suppression ratio can be improved by achieving a higher extinction ratio in the modulator and adjusting the modulator bias voltage, thereby mitigating the impact of interference frequencies. For example... Figure 3 As shown, the extinction ratio of the electro-optic IQ modulator sub-modulator is 30dB, f c At 35GHz, the positive first-order carrier suppression single-sideband modulation output corresponds to a sideband suppression ratio of approximately 25dB.

[0093] The light generated by the narrowband laser 2020, after having its polarization state adjusted by the polarization controller 2070, enters the loop from the first input terminal of the 1:1 2×2 coupler 2080. After frequency shifting by the electro-optic IQ modulator 2100, the optical signal undergoes power compensation by the erbium-doped fiber amplifier 2110. The optical bandpass filter 2120 controls the number of cycles and reduces noise accumulation; a portion of the output optical signal is output from the first output terminal of the 1:1 2×2 coupler 2080, while another portion of the optical signal re-enters the loop from the second input terminal of the 1:1 2×2 coupler 2080 and the newly input optical signal from the narrowband laser 2020 through the coupler.

[0094] Optical frequency comb generation. After N cycles, the output frequency of the 1:1 2×2 coupler 2080 is... or The optical signal. Specifically, such as Figure 4 As shown; where, Figure 4 (a) is the optical frequency comb generating signal under the ideal case, i.e., a high extinction ratio electro-optic IQ modulator; Figure 4 (b) is an optical frequency comb signal generated based on cyclic frequency shifting under actual conditions, i.e., based on Figure 3 The optical frequency comb generates the signal under the electro-optic IQ modulator.

[0095] More specifically, in this embodiment, the polarization controller allows the user to manually adjust the polarization state of the light entering the loop, thereby generating an optical frequency comb with lower flatness.

[0096] All optical connections use single-mode fiber. When replaced with polarization-maintaining fiber, the polarization controller can be removed.

[0097] The electro-optic IQ modulator achieves carrier-suppressed single-sideband modulation by adjusting the bias voltage.

[0098] The erbium-doped fiber amplifier is used to compensate for the loss of optical signal in the loop. The gain setting needs to be close to or equal to the loop loss value to achieve the best compensation effect. The wavelength of the narrowband laser and the required optical frequency comb bandwidth are set within the amplification bandwidth of the erbium-doped fiber amplifier.

[0099] The optical bandpass filter is used to filter out noise introduced by the erbium-doped fiber amplifier, while preventing the optical signal from looping infinitely in the loop, which would lead to excessive accumulated noise that overwhelms the signal. The center wavelength and bandwidth of the optical bandpass filter jointly control the number of teeth on the optical frequency comb.

[0100] According to the matrix multiplication-based optical forward error correction coding method provided by the present invention, the following steps are performed using the matrix multiplication-based optical forward error correction coding device described above:

[0101] Step 1, electrical signal generation. During the loop time [iτ, (i+1)τ), the generator matrix RF signal generator 2030 sends the i-th row (i = 1, 2, ..., M) signal, with each bit signal lasting... Time, where M is the length of the transmitted signal, τ is the time delay of one loop, and K is the number of columns in the generator matrix, which corresponds to an M×K matrix; the transmitted signal RF signal generator 2040 transmits the i-th signal within the time interval [iτ, (i+1)τ), and the two signals are multiplied by the multiplier 2050. The transmitted signal s, the generator matrix G, and the output signal s of the multiplier 2050 in the i-th loop are also considered. i The mathematical form is as follows, where a i Let s represent the i-th element (i = 1, 2, ..., M), and b ij Let G be the element in the i-th row and j-th column (i = 1, 2, ..., M; i = 1, 2, ..., K):

[0102] s = [a1, a2, ..., a M (1)

[0103]

[0104] s i =[a i b i1 a i b i2 , ..., a i b iK ],t∈[iτ,(i+1)τ) (3)

[0105] Step two: The electrical signal is converted into an optical signal. The output signal of multiplier 2050 is sent to electro-optic intensity modulator 2060 to realize the electro-optic signal conversion. The electro-optic intensity modulator adopts a push-pull structure and can be based on material platforms such as silicon and lithium niobate. Within the time interval [iτ, (i+1)τ), the input optical signal intensity is E0, and the output optical signal intensity is... Where V π1 It is the half-wave voltage of the electro-optic intensity modulator 2060.

[0106] Step 3: Optical signal storage and transmission. The output signal of the electro-optic intensity modulator 2060, after passing through the polarization controller 2070, is input into the loop via the first input terminal of the 1:1 2×2 coupler 2080. After M cycles, the output signal of the first output terminal of the 1:1 2×2 coupler 2080 has the following form, the specific form depending on whether the carrier-suppressed single-sideband retains the positive first-order sideband or the negative first-order sideband. When the positive first-order sideband is retained, the output signal form is E. OFC1 When the negative first-order sideband is retained, the output signal is in the form of E. OFC2 :

[0107]

[0108] Among them, V π2 It is the half-wave voltage of the sub-modulator of the electro-optic IQ modulator 2100, V pp It is the peak voltage of the sinusoidal signal output by the 2090 RF signal generator, V. bias It is the DC bias voltage of the electro-optic IQ modulator 2100, J ±1 (x) is the corresponding Bessel function. It is the additional phase change introduced into the optical signal in the i-th cycle, which is specifically related to parameters such as the optical loop length.

[0109] Step four: The optical signal is converted into an electrical signal. After being output from the first output terminal of the 1:1 2×2 coupler 2080, the optical signal is transmitted through optical fiber to the photodetector 2130. The output electrical signal y of the photodetector is related to the intensity I(x) of the input optical signal, i.e. Here Operators represent the conjugate of variables. In this invention, taking a positive first-order sideband carrier-suppressed single-sideband signal as an example, the photodetector 2130 outputs an electrical signal s. PD The format is as follows, here l is a variable substitution made in the formula for distinction, and is essentially the same as i.

[0110]

[0111]

[0112] To simplify formula (6), a proportionality parameter c is introduced. il and parameters Converting the proportional operator ∝ into an equation, the output electrical signal of the photodetector 2130 after conversion is as follows:

[0113]

[0114] Based on the specific conditions of the optical loop, the bandwidth of the low-pass filter 2140 is dynamically set to retain the frequency component i=1 and filter out redundant frequency waves. The corresponding output is as follows:

[0115]

[0116] From the front As can be seen from the definition and formula (3), Proportional to The value of K here has the same meaning as the variable with the same name defined in the previous formula (2), representing the number of columns of the generating matrix G. During the process of converting optical signals into electrical signals, the information stored on each optical frequency comb is added together to realize the addition of each row of the matrix. Formula (8) can be rewritten as follows:

[0117]

[0118] Where A j (j = 1, 2, ..., K) are the coefficients introduced in the step described above. i The variables with the same names in formula (5) have the same meaning, representing the i-th element of the transmitted signal s, b iK The variable with the same name in formula (2) has the same meaning, representing the element in the i-th row and K-th column of the generating matrix G.

[0119] Step 5, electrical signal decoding processing. The subsequent processing involves the low-pass filter output signal s. out The final encoded signal is obtained by performing sampling, amplification, quantization, and finite field transformation.

[0120] In this embodiment, the specific simulation parameters are as follows: the wavelength of the narrowband laser 2020 is 1550nm, the electro-optic IQ modulator 2100 is in an ideal state, i.e., the single sideband is completely suppressed, retaining the positive first-order sideband, and the noise effect of the erbium-doped fiber amplifier 2110 is not considered. The information bit length used for testing is 3, the encoding scheme is LDPC, and the encoding method is based on the multiplication of the generator matrix. The generator matrix is ​​in the following form:

[0121]

[0122] like Figure 5 As shown, the encoder output results are presented based on different input data; among them, Figure 5 (a): Input data 07, corresponding to the binary bit sequence [0 0 0 1 1 1]; Figure 5 (b): Input data 16, corresponding to the binary bit sequence [0 01 1 1 0]; Figure 5 (c): Input data 25, corresponding to the binary bit sequence [0 1 0 10 1]; Figure 5(d): Input data 34, corresponding to the binary bit sequence [1 0 1 1 0 0].

[0123] To compare the effects of this invention, this embodiment implements simulations of the OptiSystem coding scheme and the MATLAB coding scheme based on this invention, and uses a MATLAB decoder uniformly. The frame length is 500, and the ingress sequence length is 1. The bit error rate curve obtained under the OOK transmission scenario considering the Additive White Gaussian Noise (AWGN) channel is shown below. Figure 6 As shown. The results obtained by the preferred embodiment of the present invention are close to the performance of current electronic encoder solutions.

[0124] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0125] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An optical forward error correction coding device based on matrix multiplication, characterized in that, include: Narrowband laser, generator matrix RF signal generator, transmission signal RF signal generator, multiplier, electro-optic intensity modulator, optical frequency comb generation system, photodetector and low-pass filter; The output terminals of the generator matrix RF signal generator and the transmission signal RF signal generator are electrically connected to the input terminal of the multiplier, and the output terminal of the multiplier is electrically connected to the input terminal of the electro-optic intensity modulator. The output of the narrowband laser is optically connected to the input of the electro-optic intensity modulator, and the output of the electro-optic intensity modulator is optically connected to the input of the optical frequency comb generation system; the output of the optical frequency comb generation system is optically connected to the input of the photodetector, and the output of the photodetector is electrically connected to the input of the low-pass filter. The optical frequency comb generation system includes: a polarization controller, a 1:1 2×2 coupler, an electro-optic IQ modulator, a sinusoidal signal RF signal generator, an erbium-doped fiber amplifier, and an optical bandpass filter; The output of the electro-optic intensity modulator is optically connected to the input of the polarization controller. The output of the polarization controller is optically connected to the first input of the 1:1 2×2 coupler. The second output of the 1:1 2×2 coupler, the electro-optic IQ modulator, the erbium-doped fiber amplifier, the optical bandpass filter, and the second input of the 1:1 2×2 coupler are sequentially optically connected to form a loop. The output of the sinusoidal signal RF generator is electrically connected to the input of the electro-optic IQ modulator. The first output of the 1:1 2×2 coupler is optically connected to the input of the photodetector.

2. The optical forward error correction coding device based on matrix multiplication according to claim 1, characterized in that, The electro-optic IQ modulator achieves carrier-suppressed single-sideband modulation by adjusting the bias voltage.

3. The optical forward error correction coding device based on matrix multiplication according to claim 1, characterized in that, The 1:1 2×2 coupler can be replaced with couplers with a splitting ratio of 30:70 or 10:90 to ensure that the optical power at the second output end is not less than the optical power at the first output end and the optical power at the second input end is not less than the optical power at the first input end.

4. An optical forward error correction coding method based on matrix multiplication, characterized in that, The following steps are performed using any one of the matrix multiplication-based optical forward error correction coding devices according to claims 1 to 3: Step S1: Multiply the two signals generated by the generator matrix RF signal generator and the transmission signal RF signal generator through a multiplier to generate an electrical signal; Step S2: Output the electrical signal from the multiplier to the electro-optic intensity modulator to achieve electro-optic signal conversion; Step S3: Store the optical signal output by the electro-optic intensity modulator in the optical signal of the corresponding frequency of the optical frequency comb based on the optical frequency comb generation system; Step S4: Input the signal output from the optical frequency comb generation system into the photodetector to obtain an electrical signal; Step S5: The electrical signal is input to a low-pass filter to remove redundant frequencies, and then the final encoded signal is obtained.

5. The optical forward error correction coding method based on matrix multiplication according to claim 4, characterized in that, Step S1 adopts the following: During loop time In the middle, the generator matrix RF signal generator sends the first... line signal, Each signal continues Time, among which, It is the number of rows in the generated matrix. It's the time delay for one loop. This is the number of columns in the generated matrix, and the corresponding generated matrix is... matrix; Transmitting signal radio frequency signal generator in Send within the time limit One signal, among which ; It is the length of the transmitted signal; in, The first digit of the transmitted signal s One element; Denotes the first generation matrix G. Line 1 Column elements; The electrical signals generated by the multiplier include: 。 6. The optical forward error correction coding method based on matrix multiplication according to claim 4, characterized in that, Step S2 adopts the following approach: in time Inside, the input optical signal intensity of the narrowband laser is The output optical signal intensity of the electro-optic intensity modulator is ,in, It is the half-wave voltage of the electro-optic intensity modulator; Indicates the multiplier in The electrical signal output during time.

7. The optical forward error correction coding method based on matrix multiplication according to claim 4, characterized in that, The step S3 adopts the following output signal form of the first output terminal of the 1:1 2×2 coupler, the specific form of which depends on whether the carrier suppression single sideband retains the positive first-order sideband or the negative first-order sideband. When the positive first-order sideband is retained, the output signal is in the form of ; When the negative first-order sideband is retained, the output signal is in the form of : in, This represents the total output signal intensity of a 2×2 coupler with a 1:1 ratio under positive first-order carrier suppression single-sideband modulation after M cycles. This represents the total output signal intensity of a 2×2 coupler with a 1:1 ratio under negative first-order carrier suppression single-sideband modulation after M cycles. This indicates the output electrical signal of the multiplier in the m-th cycle. It is the corresponding Bessel function. It is the peak voltage of the sinusoidal signal output by the sinusoidal signal RF signal generator. This represents the sub-modulator half-wave voltage of the electro-optic IQ modulator. It is the DC bias voltage of the electro-optic IQ modulator; This indicates the frequency of the single-wavelength optical signal output by the narrowband laser. This indicates the frequency of the sinusoidal signal output by the RF signal generator. This indicates the additional phase introduced by the optical signal during loop circulation.

8. The optical forward error correction coding method based on matrix multiplication according to claim 4, characterized in that, The optical frequency comb generation system needs to ensure that the bandwidth meets the requirements: ;in, It is the number of comb teeth required, and is an integer multiple of the length of the encoded signal; It is the frequency interval of the optical frequency comb signal.

9. The optical forward error correction coding method based on matrix multiplication according to claim 4, characterized in that, The photodetector converts the signal output by the optical frequency comb generation system into an electrical signal. In the process of converting optical signals into electrical signals, the photodetector adds the information stored in the optical frequency comb teeth to achieve the addition of each row of the matrix.

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