High-speed optical signal parallel receiving device and method

Abstract

The application belongs to optical communication transmission, and discloses a high-speed optical signal parallel receiving device and method. The device comprises a spectrum shift module, a parallel photoelectric receiving module and a digital signal processing module, and the parallel photoelectric receiving module is connected with the spectrum shift module and the digital signal processing module respectively. The spectrum shift module is used for receiving an optical modulation signal, shifting high-frequency components in the spectrum of the optical modulation signal to low-frequency components, and outputting an aliasing modulation signal to the parallel photoelectric receiving module. The parallel photoelectric receiving module is used for performing low-pass filtering and analog-digital conversion on the aliasing modulation signal, and outputting a low-frequency aliasing modulation signal to the digital signal processing module. The digital signal processing module is used for recovering the optical modulation signal according to the low-frequency aliasing modulation signal, and demodulating the optical modulation signal to obtain a target signal. In the above manner, the parallel receiving of high-bandwidth analog signals is realized, and the analog bandwidth required by photoelectric devices at the receiving end is greatly reduced.

Description

Technical Field

[0001] This invention relates to optical communication transmission, and more particularly to a high-speed parallel optical signal receiving device and method. Background Technology

[0002] In high-speed optical fiber communication systems, optical signals are received by shifting the optical modulation signal to the baseband via frequency modulation (PD). Assuming the analog bandwidth of the optical modulation signal is B, the analog bandwidth of all optoelectronic devices must be ≥ B to achieve better demodulation of the optical signal. Increasing the baud rate of the optical modulation signal is the most effective way to improve the single-wavelength transmission rate. This requires a corresponding increase in the analog bandwidth of optoelectronic devices, gradually approaching the bandwidth limit of CMOS technology. The difficulty and cost of increasing the analog bandwidth will increase significantly, making the analog bandwidth of optoelectronic devices one of the bottlenecks restricting the improvement of single-wavelength optical communication rates. Therefore, developing new high-speed optical signal reception methods to fundamentally reduce the demand for analog bandwidth in optoelectronic devices is increasingly becoming a consensus and research hotspot in the optical communication industry.

[0003] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The main objective of this invention is to provide a high-speed parallel optical signal receiving device and method, which aims to solve the technical problem that the single-wavelength optical communication rate is difficult to further improve due to the limitation of analog bandwidth of optoelectronic devices in the prior art.

[0005] To achieve the above objectives, the present invention provides a high-speed optical signal parallel receiving device, comprising a spectrum shifting module, a parallel photoelectric receiving module, and a digital signal processing module, wherein the parallel photoelectric receiving module is connected to the spectrum shifting module and the digital signal processing module respectively.

[0006] The spectrum shifting module is used to receive the optical modulation signal, shift the high-frequency components in the spectrum of the optical modulation signal to the low-frequency components, and output the aliased modulation signal to the parallel photoelectric receiving module.

[0007] The parallel optoelectronic receiving module is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module.

[0008] The digital signal processing module is used to recover the optical modulation signal based on the low-frequency aliasing modulation signal, and demodulate the optical modulation signal to obtain the target signal.

[0009] Optionally, the high-speed optical signal parallel receiving device is applied to a direct detection optical transmission system, the spectrum shifting module includes a dual-output modulation unit, the parallel optoelectronic receiving module includes two parallel receiving units, and the dual-output modulation unit and the digital signal processing module are respectively connected to the two parallel receiving units;

[0010] The dual-output modulation unit is used to shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components, and output two aliased modulation signals, which are respectively transmitted to two connected parallel receiving units.

[0011] The parallel receiving unit is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module.

[0012] Optionally, the high-speed optical signal parallel receiving device is applied to a coherent optical transmission system. The spectrum shifting module includes two dual-output modulation units. The parallel optoelectronic receiving module includes a first polarization beamsplitter, a second polarization beamsplitter, two polarization-maintaining beamsplitters, four mixers, and eight parallel receiving units. The first polarization beamsplitter is connected to the two dual-output modulation units, the second polarization beamsplitter is connected to the two polarization-maintaining beamsplitters, each pair of parallel receiving units is connected to a mixer, and each pair of mixers is connected to a polarization-maintaining beamsplitter and a dual-output modulation unit.

[0013] The first polarization beam splitter is used to receive the optical modulation signal and split the optical modulation signal into two optical modulation signals polarized in a preset direction, which are then transmitted to two dual-output modulation units respectively. The preset direction includes a first direction and a second direction, wherein the first direction is perpendicular to the second direction.

[0014] The dual-output modulation unit is used to shift the high-frequency component of the spectrum of the optical modulation signal polarized in the corresponding preset direction to the low-frequency component, and output two aliased modulation signals polarized in the corresponding preset direction, which are respectively transmitted to two connected mixers.

[0015] The second polarization beam splitter is used to receive the local oscillator signal and split the local oscillator signal into two local oscillator signals polarized in the preset direction, which are then transmitted to two polarization-maintaining beam splitters respectively.

[0016] The polarization-maintaining beam splitter is used to maintain the polarization of the local oscillator signal in the corresponding preset direction and split it into two polarized local oscillator signals, which are then transmitted to two connected mixers respectively.

[0017] The mixer is used to adjust the aliasing modulation signal according to the polarization local oscillator signal, and output two adjusted aliasing modulation signals to two connected parallel receiving units.

[0018] The parallel receiving unit is used to perform low-pass filtering and analog-to-digital conversion on the received aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module.

[0019] Optionally, the digital signal processing module is further configured to add the low-frequency aliasing modulation signals of each group to recover the corresponding low-frequency signal, subtract the low-frequency aliasing modulation signals of each group to recover the corresponding high-frequency signal, and recover the optical modulation signal based on the low-frequency signal and high-frequency signal recovered from each group of low-frequency aliasing modulation signals.

[0020] Optionally, the dual-output modulation unit is further configured to shift the conjugate signal corresponding to the high-frequency signal in the optical modulation signal to a low-frequency signal when the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal;

[0021] The digital signal processing module is further configured to subtract each group of low-frequency aliasing modulation signals when the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, and recover the conjugate signal of the corresponding high-frequency signal, and recover the corresponding high-frequency signal based on the conjugate signal of the high-frequency signal corresponding to each group of low-frequency aliasing modulation signals.

[0022] Optionally, the dual-output modulation unit is further configured to shift the conjugate signal of the high-frequency signal and the low-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal and greater than or equal to half the bandwidth of the optical modulation signal.

[0023] When the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal, but greater than or equal to half the bandwidth of the optical modulation signal, the low-frequency aliasing modulation signals of each group are subtracted to recover the sum of the conjugate signals of the corresponding high-frequency signal and the corresponding low-frequency signal. Based on the low-frequency signal corresponding to each group of low-frequency aliasing modulation signals, the conjugate signal of the corresponding low-frequency signal is recovered. Based on the sum of the low-frequency aliasing modulation signals of each group and the conjugate signal of the low-frequency signal, the corresponding high-frequency signal is recovered.

[0024] Optionally, the digital signal processing module is further configured to perform low-pass filtering on the received low-frequency aliasing modulation signal.

[0025] Optionally, the parallel receiving unit includes a photodetector, a transimpedance amplifier, and an analog-to-digital converter connected in sequence.

[0026] Optionally, the dual-output modulation unit is a dual-output Mach-Zehnder modulator.

[0027] Furthermore, to achieve the above objectives, the present invention also proposes a high-speed optical signal parallel reception method, the high-speed optical signal parallel reception method comprising:

[0028] Receive an optical modulation signal, and shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components to obtain an aliasing modulation signal;

[0029] The aliased modulation signal is subjected to low-pass filtering and analog-to-digital conversion to obtain a low-frequency aliased modulation signal;

[0030] The optical modulation signal is recovered from the low-frequency aliasing modulation signal, and the optical modulation signal is demodulated to obtain the target signal.

[0031] In this invention, the high-speed optical signal parallel receiving device includes a spectrum shifting module, a parallel optoelectronic receiving module, and a digital signal processing module. The parallel optoelectronic receiving module is connected to the spectrum shifting module and the digital signal processing module, respectively. The spectrum shifting module is used to receive the optical modulation signal, shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components, and output the aliased modulation signal to the parallel optoelectronic receiving module. The parallel optoelectronic receiving module is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output the low-frequency aliased modulation signal to the digital signal processing module. The digital signal processing module is used to recover the optical modulation signal based on the low-frequency aliased modulation signal, and demodulate the optical modulation signal to obtain the target signal. Since increasing the single-wavelength transmission rate usually involves increasing the baud rate of the optical modulation signal, the analog bandwidth of the optoelectronic devices needs to be increased accordingly, gradually approaching its limit. Due to the limitation of the analog bandwidth of the optoelectronic devices, it is difficult to further increase the single-wavelength optical communication rate. This invention shifts the high-frequency part of the signal to the low-frequency part in the optical domain. In this way, the low-frequency part of the received baseband signal contains all the information of the modulation signal. The analog bandwidth of the optoelectronic devices only needs to meet the reception of the low-frequency part of the signal. In the digital domain, the aliased signal is spectrum shifted and processed, and the original high baud rate modulation signal can be recovered and demodulated. This enables parallel reception of high-bandwidth analog signals while significantly reducing the analog bandwidth required by the optoelectronic devices at the receiving end. At the same baud rate, the required analog bandwidth of the optoelectronic devices can be reduced to half of the original, alleviating the pressure of increasing the analog bandwidth of high-speed optoelectronic devices and enabling further improvement of the single-wavelength signal baud rate. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the first embodiment of the high-speed optical signal parallel receiving device of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of a second embodiment of the high-speed optical signal parallel receiving device of the present invention;

[0034] Figure 3 This is a schematic diagram of the spectrum shifting and spectrum recovery process when the frequency equals the bandwidth in an embodiment of the high-speed optical signal parallel receiving device of the present invention;

[0035] Figure 4 This is a schematic diagram of the spectrum shifting and spectrum recovery process when the frequency is equal to half the bandwidth in an embodiment of the high-speed optical signal parallel receiving device of the present invention;

[0036] Figure 5 This is a detailed structural diagram of the direct detection optical receiver according to an embodiment of the high-speed optical signal parallel receiving device of the present invention;

[0037] Figure 6 This is a schematic diagram of a dual-output Mach-Zehnder modulator structure according to an embodiment of the high-speed optical signal parallel receiving device of the present invention.

[0038] Figure 7 This is a schematic diagram of the spectral characteristics of a dual-output Mach-Zehnder modulator in an embodiment of the high-speed optical signal parallel receiving device of the present invention.

[0039] Figure 8 This is a schematic diagram of the structure of the third embodiment of the high-speed optical signal parallel receiving device of the present invention;

[0040] Figure 9 This is a schematic diagram of a detailed coherent optical receiving structure according to an embodiment of the high-speed optical signal parallel receiving device of the present invention.

[0041] Figure 10 This is a flowchart illustrating the first embodiment of the high-speed optical signal parallel reception method of the present invention.

[0042] Explanation of icon numbers:

[0043] label name label name 10 Spectrum shifting module 203 polarization maintaining beam splitter 20 Parallel photoelectric receiver module 204 mixer 30 Digital signal processing module 1011 Dual-output Mach-Zehnder modulator 101 Dual-output modulation unit 2011 Photodetector 201 Parallel receiving unit 2012 Transimpedance amplifier 202a First polarization beam splitter 2013 Analog-to-digital converter 202b Second polarization beam splitter

[0044] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0045] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0048] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0049] Reference Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the high-speed optical signal parallel receiving device of the present invention. The present invention proposes a first embodiment of the high-speed optical signal parallel receiving device.

[0050] In this embodiment, the high-speed optical signal parallel receiving device includes a spectrum shifting module 10, a parallel photoelectric receiving module 20, and a digital signal processing module 30. The parallel photoelectric receiving module 20 is connected to the spectrum shifting module 10 and the digital signal processing module 20, respectively.

[0051] It should be noted that high-speed optical signal parallel receiving devices are typically used to receive high-speed optical signals and can be applied to coherent optical transmission systems as well as direct detection optical transmission systems. This embodiment does not impose any restrictions on this.

[0052] It is understood that the spectrum shifting module 10 is used to receive the optical modulation signal, shift the high-frequency components in the spectrum of the optical modulation signal to the low-frequency components, and output the aliased modulation signal to the parallel photoelectric receiving module 20.

[0053] It should be understood that the optical signal transmitted by the transmitting end is usually modulated, that is, an optical modulation signal. It can be coherent modulation or incoherent modulation, such as intensity modulation. It can be adjusted according to the actual application requirements, and this embodiment does not limit it.

[0054] It should be noted that in this embodiment, the spectrum shifting module 10 performs spectrum shifting on the received optical modulation signal. The spectrum of the optical modulation signal is multiplied by the fundamental frequency and the first harmonic, shifting the high-frequency components in the spectrum to low-frequency components, thus achieving spectrum shifting in the optical domain. After spectrum shifting, the high-frequency and low-frequency components of the optical modulation signal will be aliased, i.e., an aliased modulation signal. The spectrum shifting module 10 is typically driven by a clock signal; the specific process of spectrum shifting differs depending on the clock signal frequency.

[0055] It should be understood that the parallel photoelectric receiving module 20 is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module 30.

[0056] It should be noted that by shifting high-frequency components of the optical modulation signal's spectrum to low-frequency components in the optical domain, the low-frequency portion of the output signal contains all the information of the optical modulation signal. Therefore, subsequent signal reception only needs to satisfy the reception of the low-frequency portion of the signal. Consequently, the analog bandwidth required by the parallel optoelectronic receiving module 20 only needs to satisfy the reception of the low-frequency portion of the signal. The parallel optoelectronic receiving module 20 typically includes multiple optoelectronic devices. Since increasing the single-wavelength transmission rate usually involves increasing the baud rate of the optical modulation signal, the analog bandwidth of the optoelectronic devices needs to be increased accordingly. In this embodiment, during signal reception, the analog bandwidth of these optoelectronic devices can be reduced, alleviating the pressure of increasing the analog bandwidth of the optoelectronic devices.

[0057] Understandably, the parallel optoelectronic receiving module 20 performs low-pass filtering on the received aliased modulation signal, filtering out the high-frequency part and retaining only the low-frequency part. Then, it performs analog-to-digital conversion, and the resulting signal is the low-frequency aliased modulation signal, which is then output to the digital signal processing module (DSP) 30.

[0058] It should be understood that the digital signal processing module 30 is used to recover the optical modulation signal based on the low-frequency aliasing modulation signal, and demodulate the optical modulation signal to obtain the target signal.

[0059] It should be noted that the target signal refers to the final electrical signal that needs to be obtained.

[0060] Understandably, although the spectrum shifting module 10 causes the high-frequency and low-frequency components of the original optical modulation signal to overlap, this overlap is predictable. The overlapped signal can be spectrum shifted and processed in the digital domain, and the original optical modulation signal can eventually be recovered and demodulated.

[0061] It should be understood that clock signals of different frequencies result in different recovery processes for optically modulated signals.

[0062] In this invention, the high-speed optical signal parallel receiving device includes a spectrum shifting module 10, a parallel optoelectronic receiving module 20, and a digital signal processing module 30. The parallel optoelectronic receiving module 20 is connected to both the spectrum shifting module 10 and the digital signal processing module 30. The spectrum shifting module 10 receives the optical modulation signal, shifts the high-frequency components of the optical modulation signal's spectrum to low-frequency components, and outputs an aliased modulation signal to the parallel optoelectronic receiving module 20. The parallel optoelectronic receiving module 20 performs low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and outputs a low-frequency aliased modulation signal to the digital signal processing module 30. The digital signal processing module 30 recovers the optical modulation signal based on the low-frequency aliased modulation signal and demodulates the optical modulation signal to obtain the target signal. Since increasing the single-wavelength transmission rate usually involves increasing the baud rate of the optical modulation signal, the analog bandwidth of the optoelectronic devices needs to be increased accordingly, gradually approaching its limit. Due to the limitation of the analog bandwidth of the optoelectronic devices, it is difficult to further increase the single-wavelength optical communication rate. In this embodiment, the high-frequency part of the signal is shifted to the low-frequency part in the optical domain. In this way, the low-frequency part of the received baseband signal contains all the information of the modulation signal. The analog bandwidth of the optoelectronic devices only needs to meet the reception of the low-frequency part of the signal. In the digital domain, the aliased signal is spectrum shifted and processed, and the original high baud rate modulation signal can be recovered and demodulated. This achieves parallel reception of high-bandwidth analog signals while significantly reducing the analog bandwidth required by the receiving optoelectronic devices. At the same baud rate, the required analog bandwidth of the optoelectronic devices can be reduced to half of the original, alleviating the pressure of increasing the analog bandwidth of high-speed optoelectronic devices and enabling further improvement of the single-wavelength signal baud rate.

[0063] Reference Figure 2 , Figure 2 This is a schematic diagram of the second embodiment of the high-speed optical signal parallel receiving device of the present invention. The present invention proposes a second embodiment of the high-speed optical signal parallel receiving device.

[0064] In this embodiment, the high-speed optical signal parallel receiving device is applied to a direct detection optical transmission system. The spectrum shifting module 10 includes a dual-output modulation unit 101, and the parallel photoelectric receiving module 20 includes two parallel receiving units 201. The dual-output modulation unit 101 and the digital signal processing module 30 are respectively connected to the two parallel receiving units 201.

[0065] It should be noted that the high-speed optical signal parallel receiving device can be applied to a direct-detection optical transmission system, where it can be considered a direct-detection optical parallel receiver. Compared to a traditional direct-detection optical parallel receiver, this embodiment adds a spectrum shifting module 10 for spectrum shifting at the receiving end. Since the dual-output modulation unit 101 is dual-output, it will output two signals, requiring two parallel receiving units 201. These two parallel receiving units 201 can be considered as a set of parallel receiving units 201.

[0066] It is understood that the dual-output modulation unit 101 is used to shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components, and output two aliased modulation signals, which are respectively transmitted to two connected parallel receiving units 201.

[0067] It should be understood that the dual-output modulation unit 101 performs spectrum shifting on the received optical modulation signal. The spectrum of the optical modulation signal is multiplied by the fundamental frequency and the first harmonic, respectively, shifting the high-frequency components in the spectrum to the low-frequency components, and outputting two aliased modulation signals, which are transmitted to two parallel receiving units 201 respectively.

[0068] It should be noted that the parallel receiving unit 201 is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module 30.

[0069] It is understood that each parallel receiving unit 201 receives one aliased modulation signal output from the dual-output modulation unit 101. In this embodiment, the dual-output modulation unit 101 outputs two aliased modulation signals, and each of the two parallel receiving units 201 receives one aliased modulation signal. The two parallel receiving units 201 respectively perform low-pass filtering on the received aliased modulation signals, filtering out the high-frequency components and retaining only the low-frequency components. At this time, the analog bandwidth required by the parallel receiving unit 201 only needs to satisfy the reception of the low-frequency components of the signal. Therefore, in this embodiment, when receiving signals, the analog bandwidth of the optoelectronic devices in the parallel receiving unit 201 can be reduced, alleviating the pressure on increasing the analog bandwidth of the optoelectronic devices.

[0070] Furthermore, the digital signal processing module 30 is also used to add the low-frequency aliasing modulation signals of each group to recover the corresponding low-frequency signal, subtract the low-frequency aliasing modulation signals of each group to recover the corresponding high-frequency signal, and recover the optical modulation signal based on the low-frequency signal and high-frequency signal recovered from each group of low-frequency aliasing modulation signals.

[0071] It should be understood that the two low-frequency aliasing modulation signals output by a set of parallel receiving units 201 constitute a set. Since this embodiment only has one set of parallel receiving units 201, there is only one set of low-frequency aliasing modulation signals. The digital signal processing module 30 receives one set of low-frequency aliasing modulation signals, i.e., two low-frequency aliasing modulation signals. The digital signal processing module 30 adds the two received low-frequency aliasing modulation signals to recover the low-frequency signal, and subtracts the two received low-frequency aliasing modulation signals. After appropriate processing, the high-frequency signal can be recovered. Both the recovered high-frequency and low-frequency signals need to be normalized. Then, the high-frequency signal is up-converted and added to the low-frequency signal to recover the original optical modulation signal.

[0072] It should be noted that the specific process of spectrum shifting by the dual-output modulation unit 101 differs for clock signals of different frequencies, and correspondingly, the specific process of signal recovery by the digital signal processing module 30 differs for clock signals of different frequencies.

[0073] Furthermore, the dual-output modulation unit 101 is also used to shift the conjugate signal corresponding to the high-frequency signal in the optical modulation signal to a low-frequency signal when the frequency of the clock driving signal is greater than or equal to the bandwidth of the optical modulation signal; the digital signal processing module 30 is also used to subtract each group of low-frequency aliased modulation signals to recover the conjugate signal of the corresponding high-frequency signal when the frequency of the clock driving signal is greater than or equal to the bandwidth of the optical modulation signal, and to recover the corresponding high-frequency signal based on the conjugate signal of the high-frequency signal corresponding to each group of low-frequency aliased modulation signals.

[0074] It is understandable that the clock drive signal is the clock signal that drives the spectrum shifting module 10. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, after spectrum shifting, the conjugate signal corresponding to the high-frequency signal in the optical modulation signal will be shifted to the low-frequency signal. That is, the conjugate signal of the high-frequency signal is shifted and superimposed on the low-frequency signal. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, the low-frequency signal of the optical modulation signal can be recovered by adding the spectra of the two low-frequency aliased modulation signals, and the conjugate signal of the high-frequency signal can be recovered by subtracting them. Taking the conjugate of the conjugate signal of the high-frequency signal can recover the high-frequency signal. Both the recovered high-frequency signal and the low-frequency signal need to be normalized. Then, the high-frequency signal is up-converted and added to the low-frequency signal to recover the original optical modulation signal.

[0075] like Figure 3 The diagram shown illustrates the spectrum shifting and recovery process when the frequency equals the bandwidth. It assumes the analog bandwidth of the original high-baud-rate optical modulation signal is f. 2c Low-frequency signal A and high-frequency signal B each occupy half of the optical modulation signal bandwidth. If the frequency of the driving clock signal is f... 2cThen the frequency difference between the first harmonic and the fundamental frequency in the dual-output modulation unit 101 is f. 2c The bandwidth is the same as that of the optical modulation signal. After the spectrum shifting by the dual-output modulation unit 101, the spectrum of the optical modulation signal is multiplied by the fundamental frequency and the first harmonic, respectively. The conjugate signal B* of the high-frequency signal B is shifted and superimposed on the low-frequency signal A. Since the first harmonics of the upper and lower signals in the dual-output modulation unit 101 are of the same magnitude but opposite in direction, the shifted spectrum will appear in opposite directions. The receiving end digital signal processing module 30 first filters out f c The high-frequency components mentioned above, when added together, yield the low-frequency signal A after filtering the two low-frequency aliased modulation signals; when subtracted, yield the conjugate signal B* of the high-frequency signal. After operations such as conjugation and normalization, the original high-baud rate optical modulation signal can be recovered. Figure 3 In this context, r is the ratio of the first harmonic to the fundamental frequency, and it represents the amplification factor during the spectral shifting process. Furthermore, Figure 3 The process only shows the positive frequency part; the negative frequency part can be processed in the same way.

[0076] Furthermore, the dual-output modulation unit 101 is further configured to shift the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock driving signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal; the digital signal processing module 30 is further configured to subtract each group of low-frequency aliased modulation signals when the frequency of the clock driving signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, recover the sum of the corresponding high-frequency signal and the conjugate signal of the corresponding low-frequency signal, recover the conjugate signal of the corresponding low-frequency signal based on the low-frequency signal corresponding to each group of low-frequency aliased modulation signals, and recover the corresponding high-frequency signal based on the sum of the low-frequency aliased modulation signals and the conjugate signal of the low-frequency signal.

[0077] It should be understood that when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, after spectrum shifting, the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal are shifted to the low-frequency signal. That is, in addition to the high-frequency signal being shifted to the low frequency, the conjugate signal of the low-frequency signal is also shifted to the position of the low-frequency signal, and the shifted conjugate signal of the high-frequency signal is superimposed on the low-frequency signal. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, adding the spectra of the two low-frequency aliased modulation signals can recover the low-frequency signal of the optical modulation signal; subtracting them can recover the conjugate signal of the high-frequency signal; taking the conjugate of the conjugate signal of the high-frequency signal can recover the high-frequency signal. Both the recovered high-frequency and low-frequency signals need to be normalized. Then, the high-frequency signal is up-converted and added to the low-frequency signal to recover the original optical modulation signal.

[0078] like Figure 4 The diagram shown illustrates the spectrum shifting and recovery process when the frequency is equal to half the bandwidth. It assumes the analog bandwidth of the original high-baud-rate optical modulation signal is f. 2c Low-frequency signal A and high-frequency signal B each occupy half of the optical modulation signal bandwidth. If the frequency of the driving clock signal is f... c Then the frequency difference between the first harmonic and the fundamental frequency of the dual-output modulation unit 101 is f. c This is half the bandwidth of the optical modulation signal. After passing through the dual-output modulation unit 101, in addition to the high-frequency component B being shifted to a low frequency, the conjugate signal A* of the low-frequency component is also shifted to the position of the original low-frequency signal A. The receiver digital signal processing module 30 first filters out f. c The high-frequency components mentioned above are then added together to recover the low-frequency component A. Subtracting them yields the high-frequency component B and its conjugate signal A*. Since the low-frequency signal A has already been recovered, taking its conjugate gives A*, which in turn allows for the recovery of B. The high-frequency component B, after up-conversion, is then added to A to recover the original high-baud rate modulated signal. Figure 4 The amplification factors for the upper and lower frequency spectrum shifts are r and -r, respectively. Furthermore, Figure 4 The process only shows the positive frequency part; the negative frequency part can be processed in the same way.

[0079] As can be seen, in this embodiment, the parallel receiving unit 201 only needs to simulate a bandwidth of f. c Optoelectronic devices can achieve an analog bandwidth of f 2c The reception of optical signals reduces the analog bandwidth of optoelectronic devices by half.

[0080] Furthermore, the digital signal processing module 30 is also used to perform low-pass filtering on the received low-frequency aliasing modulation signal.

[0081] It should be noted that the signal passing through the parallel receiving unit 201 may contain residual high-frequency components. Therefore, this embodiment can further filter out the high-frequency components through a second low-pass filter to facilitate subsequent signal recovery. Low-pass filtering can be implemented using a filter, and this embodiment does not limit its application. In specific implementations, whether to perform low-pass filtering in the digital signal processing module 30 can be determined based on actual conditions; this embodiment does not limit its application in this regard.

[0082] Further, refer to Figure 5 The parallel receiving unit 201 includes a photodetector (PD) 2011, a transimpedance amplifier (TIA) 2012, and an analog-to-digital converter (ADC) 2013 connected in sequence. The dual-output modulation unit 101 is a dual-output Mach-Zehnder modulator 1011.

[0083] It is understood that this embodiment uses a dual-output MZM (mach-zehnder modulator). For example... Figure 6 As shown, the input signal is split into two equal paths, upper and lower, after passing through the first coupler. Differential clock drive signals are loaded into both paths, and a phase shifter (PS) is introduced into each path. The PS point can be adjusted using a DC signal to ensure a phase difference of π / 2 between the upper and lower optical signals. At this point, the dual-output MZM operates at the quadrature bias point, ensuring that the modulated output optical signals contain the laser's fundamental frequency, first harmonic, and higher harmonics. The frequency of the first harmonic is equal to the frequency of the clock signal, while the higher harmonics are generated by the nonlinear effect of the dual-output MZM. These two signals are then used as input to the second dual-output coupler. PS is then added to each of the two output optical paths to adjust the optical path delay, ensuring that the delays of the upper and lower optical paths are equal. Specifically, assuming the input signal frequency is f1 and the drive clock signal frequency is f... c Therefore, the spectrum of the two output signals of the dual-output MZM includes not only f1, but also harmonic frequencies f1±N*f. c (N≥1), such as Figure 7 As shown. Because the higher harmonic components are relatively small, Figure 7 Only the first harmonic component f1±f is shown. c In both output spectra, the fundamental wave f1 has the same magnitude and direction, and the first harmonic f1±f c They are equal in size but opposite in direction, exhibiting a 180° phase difference.

[0084] It should be understood that this embodiment sets up two parallel receiving units 201, each of which has a photodetector 2011, a transimpedance amplifier 2012, and an analog-to-digital converter 2013, requiring a total of two sets of photodetectors 2011, transimpedance amplifiers 2012, and analog-to-digital converters 2013. Although the number of optoelectronic devices is increased, this embodiment can significantly reduce the analog bandwidth of the optoelectronic devices.

[0085] In this embodiment, the high-speed optical signal parallel receiving device is applied to the direct detection optical transmission system. The spectrum shifting module 10 includes a dual-output modulation unit 101, and the parallel optoelectronic receiving module 20 includes two parallel receiving units 201. The dual-output modulation unit 101 and the digital signal processing module 30 are respectively connected to the two parallel receiving units 201. The dual-output modulation unit 101 is used to shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components and output two aliased modulation signals, which are respectively transmitted to the two connected parallel receiving units 201. The parallel receiving units 201 are used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signals and output low-frequency aliased modulation signals to the digital signal processing module 30. This embodiment shifts the high-frequency portion of the signal to the low-frequency portion in the optical domain. Thus, the low-frequency portion of the received baseband signal contains all the information of the modulated signal. The analog bandwidth of the optoelectronic device only needs to meet the reception of the low-frequency portion of the signal. In the digital domain, the aliased signal is spectrum shifted and processed, ultimately recovering and demodulating the original high-baud-rate modulated signal. While achieving parallel reception of high-bandwidth analog signals, it significantly reduces the analog bandwidth required by the receiving optoelectronic device. At the same baud rate, the required analog bandwidth of the optoelectronic device can be reduced to half of its original value, alleviating the pressure of increasing the analog bandwidth of high-speed optoelectronic devices and enabling further improvement of the single-wavelength signal baud rate in direct-detection optical transmission systems.

[0086] Reference Figure 8 , Figure 8 This is a schematic diagram of the third embodiment of the high-speed optical signal parallel receiving device of the present invention. The present invention proposes a third embodiment of the high-speed optical signal parallel receiving device.

[0087] In this embodiment, the high-speed optical signal parallel receiving device is applied to a coherent optical transmission system. The spectrum shifting module 10 includes two dual-output modulation units 101. The parallel optoelectronic receiving module 20 includes a first polarization beamsplitter 202a, a second polarization beamsplitter 202b, two polarization-maintaining beamsplitters 203, four mixers 204, and eight parallel receiving units 201. The first polarization beamsplitter 202a is connected to the two dual-output modulation units 101, the second polarization beamsplitter 202b is connected to the two polarization-maintaining beamsplitters 203, each pair of parallel receiving units 201 is connected to a mixer 204, and each pair of mixers 204 is connected to a polarization-maintaining beamsplitter 203 and a dual-output modulation unit 101.

[0088] It should be noted that the high-speed optical signal parallel receiver can be applied to a coherent optical transmission system, and in this case, the high-speed optical signal parallel receiver can be considered a coherent optical parallel receiver. Compared to a traditional coherent optical parallel receiver, this embodiment adds a spectrum shifting module 10 for spectrum shifting at the receiving end.

[0089] It is understood that the first polarization beam splitter 202a is used to receive the optical modulation signal and split the optical modulation signal into two optical modulation signals polarized in a preset direction, which are then transmitted to two dual-output modulation units 101 respectively. The preset direction includes a first direction and a second direction, and the first direction is perpendicular to the second direction. The dual-output modulation unit 101 is used to shift the high-frequency component in the spectrum of the optical modulation signal polarized in the corresponding preset direction to a low-frequency component, and output two aliased modulation signals polarized in the corresponding preset direction, which are then transmitted to two connected mixers 204 respectively.

[0090] It should be understood that traditional coherent optical parallel receivers typically have an optical signal input, a local optical oscillator (LO) input, a polarization beam splitter (PBS), and a 90° hybrid (mixer). The local oscillator signal at the LO input beats with the input optical signal to shift the optical signal spectrum to baseband. This embodiment retains these structures, and adds a dual-output modulation unit 101. The polarization beam splitter can split the signal into two signals polarized in preset directions. The preset directions are two polarization directions, including a first direction and a second direction, which can be considered as the X and Y directions. The first and second directions are perpendicular, meaning the two polarized signals output by the polarization beam splitter are orthogonal. In this embodiment, the first polarization beam splitter 202a splits the received optical modulation signal into an X-direction polarized optical modulation signal and a Y-direction polarized optical modulation signal. The two dual-output modulation units 101 respectively receive the X-direction polarized optical modulation signal and the Y-direction polarized optical modulation signal. After the X-direction polarized light modulation signal is spectrum shifted by the dual-output modulation unit 101, it is split into two X-direction polarized aliased modulation signals and transmitted to the two connected mixers 204. After the Y-direction polarized light modulation signal is spectrum shifted by the dual-output modulation unit 101, it is also split into two Y-direction polarized aliased modulation signals and transmitted to the two connected mixers 204. The two mixers 204 corresponding to the two X-direction polarized aliased modulation signals are different from those corresponding to the two Y-direction polarized aliased modulation signals.

[0091] Furthermore, the dual-output modulation unit 101 is also configured to shift the conjugate signal corresponding to the high-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock driving signal is greater than or equal to the bandwidth of the optical modulation signal; the dual-output modulation unit 101 is also configured to shift the conjugate signal of the high-frequency signal and the low-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock driving signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal.

[0092] It should be noted that the clock drive signal is the clock signal that drives the spectrum shifting module 10. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, after spectrum shifting, the conjugate signal corresponding to the high-frequency signal in the optical modulation signal polarized in the preset direction will be shifted to the low-frequency signal. That is, the conjugate signal of the high-frequency signal is shifted and then superimposed on the low-frequency signal. When the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, after spectrum shifting, the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal polarized in the preset direction are shifted to the low-frequency signal. That is, in addition to the high-frequency signal being shifted to the low frequency, the conjugate signal of the low-frequency signal is also shifted to the position of the low-frequency signal, and the conjugate signals of the high-frequency signal and the low-frequency signal are superimposed on the low-frequency signal.

[0093] It is understood that the second polarization beam splitter 202b is used to receive the local oscillator signal and split the local oscillator signal into two local oscillator signals polarized in the preset direction, which are then transmitted to two polarization-maintaining beam splitters 203 respectively; the polarization-maintaining beam splitter 203 is used to maintain the polarization of the local oscillator signal in the corresponding preset direction and split it into two polarized local oscillator signals which are then transmitted to two connected mixers 204 respectively.

[0094] It should be understood that the second polarization beam splitter 202b will divide the received local oscillator signal into a local oscillator signal polarized in the X direction and a local oscillator signal polarized in the Y direction. Since this embodiment outputs two aliased modulation signals polarized in the X direction and two aliased modulation signals polarized in the Y direction, a corresponding number of local oscillator signals must also be output. This embodiment achieves this through a polarization maintaining beam splitter (PMBS) 203. The polarization maintaining beam splitter 203 can maintain the polarization direction of the local oscillator signal and output two signals polarized in the same preset direction, i.e., polarized local oscillator signals. One polarization-maintaining beam splitter 203 splits the received local oscillator signal polarized in the X direction into two polarized local oscillator signals polarized in the X direction. The other polarization-maintaining beam splitter 203 splits the received local oscillator signal polarized in the Y direction into two polarized local oscillator signals polarized in the Y direction. Both the two polarized local oscillator signals polarized in the X direction and the two polarized local oscillator signals polarized in the Y direction are transmitted to the mixer 204. The two polarized local oscillator signals polarized in the X direction are transmitted to the two mixers 204 that receive the optical modulation signal polarized in the X direction, and the two polarized local oscillator signals polarized in the Y direction are transmitted to the two mixers 204 that receive the optical modulation signal polarized in the Y direction.

[0095] It should be noted that the mixer 204 is used to adjust the aliasing modulation signal according to the polarization local oscillator signal, and output two adjusted aliasing modulation signals to two connected parallel receiving units 201; the parallel receiving unit 201 is used to perform low-pass filtering and analog-to-digital conversion on the received aliasing modulation signal, and output a low-frequency aliasing modulation signal to the digital signal processing module 30.

[0096] It is understandable that traditional coherent optical receivers typically use the local oscillator signal to mix with the input optical signal in an optical mixer to obtain an intermediate frequency signal whose frequency, phase, and amplitude change in the same way as the optical signal. This embodiment still adopts this method. Each mixer receives one polarization local oscillator signal and one aliased modulation signal. Therefore, in this embodiment, one polarization local oscillator signal and one aliased modulation signal are mixed in each mixer 204, and finally two adjusted aliased modulation signals are output.

[0097] It should be understood that in this embodiment, each parallel receiving unit 201 receives an adjusted aliasing modulation signal output by a mixer 204. Each parallel receiving unit 201 performs low-pass filtering on the received aliasing modulation signal to filter out the high-frequency part and retain only the low-frequency part. At this time, the analog bandwidth required by the parallel receiving unit 201 only needs to meet the reception of the low-frequency part of the signal. Therefore, in this embodiment, when receiving signals, the analog bandwidth of the optoelectronic devices in the parallel receiving unit 201 can be reduced, alleviating the pressure of increasing the analog bandwidth of the optoelectronic devices.

[0098] It should be noted that the two parallel receiving units 201 connected to each mixer 204 are considered as a group, and the low-frequency aliasing modulation signals output by a group of parallel receiving units 201 constitute a group. In this embodiment, a total of four groups of low-frequency aliasing modulation signals are output to the digital signal processing module 30. The digital signal processing module 30 receives four groups of low-frequency aliasing modulation signals, that is, eight low-frequency aliasing modulation signals.

[0099] Furthermore, the digital signal processing module 30 is also used to add the low-frequency aliasing modulation signals of each group to recover the corresponding low-frequency signal, subtract the low-frequency aliasing modulation signals of each group to recover the corresponding high-frequency signal, and recover the optical modulation signal based on the low-frequency signal and high-frequency signal recovered from each group of low-frequency aliasing modulation signals.

[0100] Understandably, after receiving four sets of low-frequency aliased modulation signals, the digital signal processing module 30 needs to recover each set of low-frequency aliased modulation signals separately. Adding each set of low-frequency aliased modulation signals recovers the low-frequency signal, and subtracting each set, after appropriate processing, recovers the high-frequency signal, resulting in four sets of high-frequency and low-frequency signals. Both the recovered high-frequency and low-frequency signals are normalized. Then, the high-frequency signal is up-converted and added to the low-frequency signal to recover the X-axis polarized light modulation signal, the Y-axis polarized light modulation signal, the X-axis polarized local oscillator signal, and the Y-axis polarized local oscillator signal, respectively. Finally, demodulation is performed to obtain the desired signal. In this embodiment, the parallel receiving unit 201 also only needs an analog bandwidth of f. c Optoelectronic devices can achieve an analog bandwidth of f 2c The reception of optical signals reduces the analog bandwidth of optoelectronic devices by half.

[0101] It should be understood that the specific process of spectrum shifting by the dual-output modulation unit 101 differs for clock signals of different frequencies, and correspondingly, the specific process of signal recovery by the digital signal processing module 30 differs for clock signals of different frequencies.

[0102] Furthermore, the dual-output modulation unit 101 is also used to shift the conjugate signal corresponding to the high-frequency signal in the optical modulation signal to a low-frequency signal when the frequency of the clock driving signal is greater than or equal to the bandwidth of the optical modulation signal; the digital signal processing module 30 is also used to subtract each group of low-frequency aliased modulation signals to recover the conjugate signal of the corresponding high-frequency signal when the frequency of the clock driving signal is greater than or equal to the bandwidth of the optical modulation signal, and to recover the corresponding high-frequency signal based on the conjugate signal of the high-frequency signal corresponding to each group of low-frequency aliased modulation signals.

[0103] It should be noted that the clock drive signal is the clock signal that drives the spectrum shifting module 10. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, after spectrum shifting, the conjugate signal corresponding to the high-frequency signal in the optical modulation signal will be shifted to the low-frequency signal. In other words, the conjugate signal of the high-frequency signal is shifted and superimposed on the low-frequency signal. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, the low-frequency signal can be recovered by adding the spectra of each group of low-frequency aliased modulation signals, and the conjugate signal of the high-frequency signal can be recovered by subtracting them. Taking the conjugate of the conjugate signal of the high-frequency signal can recover the high-frequency signal.

[0104] Furthermore, the dual-output modulation unit 101 is further configured to shift the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock driving signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal; the digital signal processing module 30 is further configured to subtract each group of low-frequency aliased modulation signals when the frequency of the clock driving signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, recover the sum of the corresponding high-frequency signal and the conjugate signal of the corresponding low-frequency signal, recover the conjugate signal of the corresponding low-frequency signal based on the low-frequency signal corresponding to each group of low-frequency aliased modulation signals, and recover the corresponding high-frequency signal based on the sum of the low-frequency aliased modulation signals and the conjugate signal of the low-frequency signal.

[0105] Understandably, when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, after spectrum shifting, the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal are shifted to the low-frequency signal. In other words, besides the high-frequency signal being shifted to the low frequency, the conjugate signal of the low-frequency signal is also shifted to the low-frequency signal's position, and the shifted conjugate signal of the high-frequency signal is superimposed on the low-frequency signal. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, the low-frequency signal of the optical modulation signal can be recovered by adding the spectra of each group of low-frequency aliased modulation signals, and the conjugate signal of the high-frequency signal can be recovered by subtracting them. Taking the conjugate of the high-frequency signal's conjugate signal can recover the high-frequency signal.

[0106] Furthermore, the digital signal processing module 30 is also used to perform low-pass filtering on the received low-frequency aliasing modulation signal.

[0107] It is understandable that the signal passing through the parallel receiving unit 201 may contain residual high-frequency components. Therefore, this embodiment can further filter out the high-frequency components through a second low-pass filter to facilitate subsequent signal recovery. Low-pass filtering can be implemented using a filter, and this embodiment does not limit its implementation. In specific implementations, whether to perform low-pass filtering in the digital signal processing module 30 can be determined based on actual conditions; this embodiment does not limit its implementation in this regard.

[0108] Further, refer to Figure 9 The parallel receiving unit 201 includes a photodetector 2011, a transimpedance amplifier 2012, and an analog-to-digital converter 2013 connected in sequence. The dual-output modulation unit 101 is a dual-output Mach-Zehnder modulator 1011. The specific structure of the dual-output Mach-Zehnder modulator 1011 can be found in [reference needed]. Figure 6 The method for achieving spectrum shifting can be referred to in the second embodiment, and will not be repeated here.

[0109] It should be understood that in this embodiment, each mixer 204 corresponds to two parallel receiving units 201, and each parallel receiving unit 201 has a photodetector 2011, a transimpedance amplifier 2012, and an analog-to-digital converter 2013. Therefore, this embodiment requires a total of 8 sets of photodetectors 2011, transimpedance amplifiers 2012, and analog-to-digital converters 2013. Although the number of optoelectronic devices is increased, this embodiment can significantly reduce the analog bandwidth of the optoelectronic devices.

[0110] In this embodiment, the high-speed optical signal parallel receiving device is applied to a coherent optical transmission system. The spectrum shifting module 10 includes two dual-output modulation units 101, and the parallel optoelectronic receiving module 20 includes a first polarization beamsplitter 202a, a second polarization beamsplitter 202b, two polarization-maintaining beamsplitters 203, four mixers 204, and eight parallel receiving units 201. The first polarization beamsplitter 202a is connected to the two dual-output modulation units 101, the second polarization beamsplitter 202b is connected to the two polarization-maintaining beamsplitters 203, each pair of parallel receiving units 201 is connected to a mixer 204, and each pair of mixers 204 is connected to a polarization-maintaining beamsplitter 203 and a dual-output modulation unit 101. This embodiment shifts the high-frequency portion of the signal to the low-frequency portion in the optical domain. Thus, the low-frequency portion of the received baseband signal contains all the information of the modulated signal. The analog bandwidth of the optoelectronic device only needs to meet the reception of the low-frequency portion of the signal. In the digital domain, the aliased signal is spectrum shifted and processed, ultimately recovering and demodulating the original high-baud-rate modulated signal. While achieving parallel reception of high-bandwidth analog signals, it significantly reduces the analog bandwidth required by the receiving optoelectronic device. At the same baud rate, the required analog bandwidth of the optoelectronic device can be reduced to half of its original value, alleviating the pressure of increasing the analog bandwidth of high-speed optoelectronic devices and enabling further improvement of the single-wavelength signal baud rate in coherent optical transmission systems.

[0111] This invention provides a method for parallel reception of high-speed optical signals, referring to... Figure 10 , Figure 10 This is a flowchart illustrating the first embodiment of a high-speed optical signal parallel reception method according to the present invention.

[0112] In this embodiment, the high-speed optical signal parallel reception method includes the following steps:

[0113] Step S10: Receive the optical modulation signal, and shift the high-frequency components in the spectrum of the optical modulation signal to the low-frequency components to obtain the aliasing modulation signal.

[0114] It should be noted that the execution entity in this embodiment is a high-speed optical signal parallel receiving device, including a spectrum shifting module, a parallel photoelectric receiving module, and a digital signal processing module. For the specific structure, please refer to... Figure 1 You can also refer to Figure 2 , 5 The following are not limited to 8 and 9 in this embodiment.

[0115] It is understandable that the optical signal transmitted by the transmitting end is usually modulated, i.e., an optically modulated signal. This embodiment performs spectrum shifting on the received optically modulated signal. The spectrum of the optically modulated signal is multiplied by the fundamental frequency and the first harmonic, shifting the high-frequency components in the spectrum to low-frequency components, thus achieving spectrum shifting in the optical domain. After spectrum shifting, the high-frequency and low-frequency components of the optically modulated signal will be aliased, i.e., an aliased modulation signal. Spectrum shifting is usually driven by a clock signal; the specific process differs depending on the clock signal frequency.

[0116] Further, the step of shifting high-frequency components in the spectrum of the optical modulation signal to low-frequency components includes: shifting the conjugate signal corresponding to the high-frequency signal in the optical modulation signal to a low-frequency signal when the frequency of the clock driving signal is greater than or equal to the bandwidth of the optical modulation signal; and shifting the conjugate signal of the high-frequency signal and the low-frequency signal in the optical modulation signal to a low-frequency signal when the frequency of the clock driving signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal.

[0117] It should be understood that the clock drive signal is the clock signal that drives the spectrum shift. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, after spectrum shifting, the conjugate signal corresponding to the high-frequency signal in the optical modulation signal will be shifted to the low-frequency signal. In other words, the conjugate signal of the high-frequency signal is shifted and then superimposed on the low-frequency signal. When the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, after spectrum shifting, the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal are shifted to the low-frequency signal. That is, in addition to the high-frequency signal being shifted to the low frequency, the conjugate signal of the low-frequency signal is also shifted to the position of the low-frequency signal, and the conjugate signals of the high-frequency signal and the low-frequency signal are superimposed on the low-frequency signal.

[0118] Step S20: Perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal to obtain a low-frequency aliased modulation signal.

[0119] It should be noted that this embodiment performs low-pass filtering on the received aliased modulation signal, filtering out the high-frequency components and retaining only the low-frequency components. Then, analog-to-digital conversion is performed, and the resulting signal is the low-frequency aliased modulation signal. Since the high-frequency components of the optical modulation signal's spectrum have already been shifted to low-frequency components in the optical domain, the low-frequency portion of the output signal contains all the information of the optical modulation signal. Therefore, subsequent signal reception only needs to satisfy the reception of the low-frequency portion of the signal. Since increasing the single-wavelength transmission rate usually involves increasing the baud rate of the optical modulation signal, the analog bandwidth of the optoelectronic devices needs to be increased accordingly. In this embodiment, the analog bandwidth of these optoelectronic devices can be reduced during signal reception, alleviating the pressure of increasing the analog bandwidth of the optoelectronic devices.

[0120] Step S30: Based on the low-frequency aliasing modulation signal, recover the optical modulation signal and demodulate the optical modulation signal to obtain the target signal.

[0121] It is understandable that the target signal refers to the final electrical signal that needs to be obtained. Although spectrum shifting causes the high-frequency and low-frequency components of the original optical modulation signal to alias, this aliasing follows a predictable pattern. The aliased signal can be spectrum shifted and processed in the digital domain to ultimately recover the original optical modulation signal and demodulate it.

[0122] Further, the step of recovering the optical modulation signal based on the low-frequency aliasing modulation signal includes: adding each group of low-frequency aliasing modulation signals to recover the corresponding low-frequency signal, subtracting each group of low-frequency aliasing modulation signals to recover the corresponding high-frequency signal, and recovering the optical modulation signal based on the low-frequency signal and high-frequency signal recovered from each group of low-frequency aliasing modulation signals.

[0123] It should be understood that adding each group of low-frequency aliased modulation signals together can recover the low-frequency signal, and subtracting each group of two low-frequency aliased modulation signals, after appropriate processing, can recover the high-frequency signal. Both the recovered high-frequency and low-frequency signals need to be normalized, and then the high-frequency signal is up-converted and added to the low-frequency signal to recover the original optical modulation signal.

[0124] It should be noted that the specific processes for spectrum shifting differ for clock signals of different frequencies, and correspondingly, the specific processes for signal recovery also differ for clock signals of different frequencies.

[0125] Further, the step of recovering the optical modulation signal based on the low-frequency aliasing modulation signal includes: when the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, subtracting each group of low-frequency aliasing modulation signals to recover the conjugate signal of the corresponding high-frequency signal; and recovering the corresponding high-frequency signal based on the conjugate signal of the high-frequency signal corresponding to each group of low-frequency aliasing modulation signals; when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, subtracting each group of low-frequency aliasing modulation signals to recover the sum of the conjugate signals of the corresponding high-frequency signal and the corresponding low-frequency signal; recovering the conjugate signal of the corresponding low-frequency signal based on the low-frequency signal corresponding to each group of low-frequency aliasing modulation signals; and recovering the corresponding high-frequency signal based on the sum of the low-frequency aliasing modulation signals and the conjugate signal of the low-frequency signal.

[0126] It is understandable that the clock drive signal is the clock signal used for driving. When the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, after spectrum shifting, the conjugate signal corresponding to the high-frequency signal in the optical modulation signal will be shifted to the low-frequency signal. The sum of the spectra of each group of low-frequency aliased modulation signals can recover the low-frequency signal of the optical modulation signal, and the subtraction can recover the conjugate signal of the high-frequency signal. Taking the conjugate of the conjugate signal of the high-frequency signal can recover the high-frequency signal. Thus, the original optical modulation signal can be recovered from the recovered high-frequency signal and low-frequency signal.

[0127] It should be understood that when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, after spectrum shifting, the high-frequency signal and the conjugate signal of the low-frequency signal in the optical modulation signal are shifted to the low-frequency signal. The spectrum of each group of low-frequency aliased modulation signals can be added together to recover the low-frequency signal of the optical modulation signal, and subtracted to recover the conjugate signal of the high-frequency signal. The conjugate signal of the high-frequency signal can be conjugated to recover the high-frequency signal. Thus, the original optical modulation signal can be recovered from the recovered high-frequency signal and low-frequency signal.

[0128] Furthermore, before step S30, the method further includes: performing low-pass filtering on the low-frequency aliasing modulation signal.

[0129] It should be noted that low-frequency aliasing modulation signals may retain residual high-frequency components. Therefore, this embodiment can use a second low-pass filter to further filter out the high-frequency components for subsequent signal recovery. Low-pass filtering can be implemented using a filter, and this embodiment does not limit its application. In specific implementations, whether to perform a second low-pass filter can be determined based on the actual situation; this embodiment does not impose any restrictions on this.

[0130] In this embodiment, by receiving an optical modulation signal, the high-frequency components in the spectrum of the optical modulation signal are shifted to low-frequency components to obtain an aliased modulation signal. The aliased modulation signal is then subjected to low-pass filtering and analog-to-digital conversion to obtain a low-frequency aliased modulation signal. Based on the low-frequency aliased modulation signal, the optical modulation signal is recovered and demodulated to obtain the target signal. Since increasing the single-wavelength transmission rate usually involves increasing the baud rate of the optical modulation signal, the analog bandwidth of the optoelectronic devices needs to be increased accordingly, gradually approaching its limit. Due to the limitation of the analog bandwidth of the optoelectronic devices, it is difficult to further increase the single-wavelength optical communication rate. In this embodiment, the high-frequency part of the signal is shifted to the low-frequency part in the optical domain. In this way, the low-frequency part of the received baseband signal contains all the information of the modulation signal. The analog bandwidth of the optoelectronic devices only needs to meet the reception of the low-frequency part of the signal. In the digital domain, the aliased signal is spectrum shifted and processed, and the original high baud rate modulation signal can be recovered and demodulated. This achieves parallel reception of high-bandwidth analog signals while significantly reducing the analog bandwidth required by the receiving optoelectronic devices. At the same baud rate, the required analog bandwidth of the optoelectronic devices can be reduced to half of the original, alleviating the pressure of increasing the analog bandwidth of high-speed optoelectronic devices and enabling further improvement of the single-wavelength signal baud rate.

[0131] It should be understood that the above are merely illustrative examples and do not constitute any limitation on the technical solutions of the present invention. In specific applications, those skilled in the art can make settings as needed, and the present invention does not impose any restrictions on this.

[0132] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of this invention. In practical applications, those skilled in the art can select some or all of the workflow to achieve the purpose of this embodiment according to actual needs, and no restrictions are imposed here.

[0133] In addition, for technical details not described in detail in this embodiment, please refer to the high-speed optical signal parallel reception method provided in any embodiment of the present invention, which will not be repeated here.

[0134] Furthermore, it should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0135] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0136] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory (ROM) / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0137] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A high-speed parallel optical signal receiving device, characterized in that, The high-speed optical signal parallel receiving device includes a spectrum shifting module, a parallel optoelectronic receiving module, and a digital signal processing module. The parallel optoelectronic receiving module is connected to the spectrum shifting module and the digital signal processing module, respectively. The spectrum shifting module is used to receive the optical modulation signal, shift the high-frequency components in the spectrum of the optical modulation signal to the low-frequency components, and output the aliased modulation signal to the parallel photoelectric receiving module. The parallel optoelectronic receiving module is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module. The digital signal processing module is used to recover the optical modulation signal based on the low-frequency aliasing modulation signal, and demodulate the optical modulation signal to obtain the target signal.

2. The apparatus as claimed in claim 1, characterized in that, The high-speed optical signal parallel receiving device is applied to a direct detection optical transmission system. The spectrum shifting module includes a dual-output modulation unit, and the parallel optoelectronic receiving module includes two parallel receiving units. The dual-output modulation unit and the digital signal processing module are respectively connected to the two parallel receiving units. The dual-output modulation unit is used to shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components, and output two aliased modulation signals, which are respectively transmitted to two connected parallel receiving units. The parallel receiving unit is used to perform low-pass filtering and analog-to-digital conversion on the aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module.

3. The apparatus as described in claim 1, characterized in that, The high-speed optical signal parallel receiving device is applied to a coherent optical transmission system. The spectrum shifting module includes two dual-output modulation units. The parallel optoelectronic receiving module includes a first polarization beamsplitter, a second polarization beamsplitter, two polarization-maintaining beamsplitters, four mixers, and eight parallel receiving units. The first polarization beamsplitter is connected to the two dual-output modulation units. The second polarization beamsplitter is connected to the two polarization-maintaining beamsplitters. Every two parallel receiving units form a group connected to a mixer. Every two mixers are connected to a polarization-maintaining beamsplitter and a dual-output modulation unit. The first polarization beam splitter is used to receive the optical modulation signal and split the optical modulation signal into two optical modulation signals polarized in a preset direction, which are then transmitted to two dual-output modulation units respectively. The preset direction includes a first direction and a second direction, wherein the first direction is perpendicular to the second direction. The dual-output modulation unit is used to shift the high-frequency component of the spectrum of the optical modulation signal polarized in the corresponding preset direction to the low-frequency component, and output two aliased modulation signals polarized in the corresponding preset direction, which are respectively transmitted to two connected mixers. The second polarization beam splitter is used to receive the local oscillator signal and split the local oscillator signal into two local oscillator signals polarized in the preset direction, which are then transmitted to two polarization-maintaining beam splitters respectively. The polarization-maintaining beam splitter is used to maintain the polarization of the local oscillator signal in the corresponding preset direction and split it into two polarized local oscillator signals, which are then transmitted to two connected mixers respectively. The mixer is used to adjust the aliasing modulation signal according to the polarization local oscillator signal, and output two adjusted aliasing modulation signals to two connected parallel receiving units. The parallel receiving unit is used to perform low-pass filtering and analog-to-digital conversion on the received aliased modulation signal, and output a low-frequency aliased modulation signal to the digital signal processing module.

4. The apparatus as described in claim 2 or 3, characterized in that, The digital signal processing module is further configured to add the low-frequency aliasing modulation signals of each group to recover the corresponding low-frequency signal, subtract the low-frequency aliasing modulation signals of each group to recover the corresponding high-frequency signal, and recover the optical modulation signal based on the low-frequency signal and high-frequency signal recovered from each group of low-frequency aliasing modulation signals.

5. The apparatus as described in claim 4, characterized in that, The dual-output modulation unit is also used to shift the conjugate signal corresponding to the high-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal. The digital signal processing module is further configured to subtract each group of low-frequency aliasing modulation signals when the frequency of the clock drive signal is greater than or equal to the bandwidth of the optical modulation signal, and recover the conjugate signal of the corresponding high-frequency signal, and recover the corresponding high-frequency signal based on the conjugate signal of the high-frequency signal corresponding to each group of low-frequency aliasing modulation signals.

6. The apparatus as claimed in claim 4, characterized in that, The dual-output modulation unit is further configured to shift the conjugate signal of the high-frequency signal and the low-frequency signal in the optical modulation signal to the low-frequency signal when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal and greater than or equal to half the bandwidth of the optical modulation signal. The digital signal processing module is further configured to subtract each group of low-frequency aliasing modulation signals when the frequency of the clock drive signal is less than the bandwidth of the optical modulation signal but greater than or equal to half the bandwidth of the optical modulation signal, to recover the sum of the corresponding high-frequency signal and the conjugate signal of the corresponding low-frequency signal, to recover the conjugate signal of the corresponding low-frequency signal based on the low-frequency signal corresponding to each group of low-frequency aliasing modulation signals, and to recover the corresponding high-frequency signal based on the sum of the corresponding low-frequency aliasing modulation signals and the conjugate signal of the low-frequency signal.

7. The apparatus as claimed in claim 4, characterized in that, The digital signal processing module is also used to perform low-pass filtering on the received low-frequency aliasing modulation signal.

8. The apparatus as claimed in claim 2 or 3, characterized in that, The parallel receiving unit includes a photodetector, a transimpedance amplifier, and an analog-to-digital converter connected in sequence.

9. The apparatus as claimed in claim 2 or 3, characterized in that, The dual-output modulation unit is a dual-output Mach-Zehnder modulator.

10. A method for parallel reception of high-speed optical signals, characterized in that, The high-speed optical signal parallel receiving method, applied to any one of claims 1 to 9, comprises: Receive an optical modulation signal, and shift the high-frequency components in the spectrum of the optical modulation signal to low-frequency components to obtain an aliasing modulation signal; The aliased modulation signal is subjected to low-pass filtering and analog-to-digital conversion to obtain a low-frequency aliased modulation signal; The optical modulation signal is recovered from the low-frequency aliasing modulation signal, and the optical modulation signal is demodulated to obtain the target signal.

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