Optical sampling pulse design and sampling bandwidth expansion method of square detection type optical receiver

Abstract

The invention discloses an optical sampling pulse design and sampling bandwidth expansion method suitable for a square detection type optical receiver. According to the method, based on system transfer function analysis and spectrum convolution characteristics, spectrum distribution of optical sampling pulses is optimized for an electric spectrum, so that the spectrum is flatter, and the sampling bandwidth of the system is expanded. Different from the existing method, the method provided by the invention provides a feasible scheme for generating the optical sampling pulse of the large-scale integrated optical receiver by regulating and controlling the amplitude relationship of the optical combs without changing the number of the existing phase-locked optical combs, additionally introducing an optical device and increasing the system complexity. The performance of the square detection type optical receiver can be effectively improved, and important support is provided for practical application of the square detection type optical receiver.

Description

Technical Field

[0001] The present invention relates to photon information processing, and specifically to an optical sampling pulse design and sampling bandwidth expansion method for a square detection optical receiver. Background Art

[0002] Traditional electrical receivers face bottlenecks in the process of high-speed signal sampling and processing. Especially in the acquisition and high-precision recovery of ultra-wideband signals, they are restricted by factors such as the bandwidth, noise, and power consumption of electronic devices. As the signal frequency and bandwidth increase, it is difficult for the performance of electrical receivers to break through further, forming the so-called "electronic bottleneck". Benefiting from the ultra-large input bandwidth of electro-optic modulators, optical receivers can overcome this limitation, give full play to the advantages of optical systems, and achieve efficient sampling and processing of ultra-wideband signals. Among them, the square detection optical receiver has received extensive attention due to its simple structure, easy integration, etc., and provides a new solution for the high-precision sampling of ultra-wideband signals.

[0003] In a square detection optical receiver, the optical sampling pulse is the key to realizing high-frequency signal reception. Its high-frequency components can fold the signals in multiple Nyquist zones back to the first Nyquist zone, enabling the subsequent low-speed electrical quantization module to effectively process the signals. Therefore, the design of a wide-spectrum optical sampling pulse is crucial for expanding the sampling bandwidth of a square detection optical receiver. In an optical receiver system, the design of the optical sampling pulse needs to meet requirements such as being simple and easy to integrate, and having a consistent sampling frequency comb phase, in order to achieve stable ultra-wideband signal sampling.

[0004] For this reason, researchers have carried out a large number of studies on wide-spectrum optical sampling pulses. In 2014, Paolo Ghelfi et al. from the National Research Council of Italy (CNIT) proposed a microwave photon radar based on a mode-locked laser, but the integration difficulty of the mode-locked laser is relatively high, and its application in optical sampling pulse generation has gradually decreased in recent years. In 2019, Xu Yirong et al. from Tsinghua University proposed an optical sampling pulse architecture based on an intensity modulator and a phase modulator and applied it to an optical receiver, but this scheme needs to introduce dispersion fiber, which not only increases the system integration difficulty but also reduces the signal-to-noise ratio. In 2021, Liu Siqi et al. from Shanghai Jiao Tong University proposed an optical sampling pulse generation architecture based on a cascaded dual-parallel modulator, generated 25 flat optical combs in the optical domain, and achieved 8 flat electrical combs within 3.5 dB in the electrical domain, but did not consider the influence of the optoelectronic conversion process on the sampling frequency comb. In 2022, the Liu Yong team from the University of Electronic Science and Technology optimized the optical sampling pulse generation architecture based on an intensity modulator and a phase modulator, making the electrical comb flatter through low-bias modulation and dispersion compensation, but did not conduct an in-depth analysis of the optoelectronic conversion relationship.

[0005] In summary, the current research on square-detection optical receivers still lacks a systematic analysis of the convolution effect from the optical comb to the electrical comb during the optoelectronic conversion process. This convolution effect causes the electrical comb to exhibit a triangular envelope with severe amplitude attenuation. Even if Nyquist pulses are generated in the optical domain, the corresponding electrical comb is still not flat, ultimately limiting the effective sampling bandwidth of the optical receiver. In addition, the design of existing wide-spectrum optical sampling pulses does not fully consider the impact of optoelectronic convolution and fails to optimize the spectral design, resulting in a limited number of available flat electrical combs. At the same time, some schemes require the introduction of additional optical devices, further increasing the integration difficulty. Therefore, there is an urgent need for an optical sampling pulse design method suitable for square-detection optical receivers. This method needs to combine the convolution relationship of optoelectronic conversion, maximize the number of flat electrical combs while ensuring the phase locking of the sampling frequency comb and the integrability of the architecture, thereby effectively expanding the sampling bandwidth of the optical receiver. Summary of the Invention

[0006] The present invention aims at the deficiencies of the prior art and proposes an optical sampling pulse design and sampling bandwidth expansion method suitable for square-detection optical receivers. This method optimizes the electrical spectrum of the square-detection optical receiver and inversely derives the design of the receiver spectrum based on the convolution conversion relationship between the optical spectrum and the electrical spectrum, thereby effectively expanding the sampling bandwidth of the receiver. Different from traditional optical sampling pulse design methods, the present invention quantitatively analyzes the convolution relationship between the optical sampling pulse spectrum and the electrical spectrum and compensates for this convolution effect during the spectral design to achieve a flatter electrical spectrum. Specifically, the present invention first establishes the convolution constraint relationship between the spectral phase-locked frequency comb and the electrical spectrum frequency comb, performs an optimal solution based on the target optimized electrical spectrum frequency comb, and finally inversely derives the required spectral design according to the optimized electrical spectrum. The present invention is based on the mature integrated Mach-Zehnder modulation structure and does not require the introduction of additional optical devices such as optical filters and dispersion fibers, thus not increasing the system complexity. Only by optimizing the amplitude relationship between existing optical combs can the electrical spectrum be made flatter, effectively expanding the sampling bandwidth of the optical receiver. This method not only improves the performance of the optical receiver but also provides important technical support for the practical application of the optical receiver, having important engineering value and application prospects.

[0007] The theoretical demonstration of the present invention is as follows:

[0008] In a receiver based on an optical sampling pulse, the signal v in (t) to be sampled is modulated onto the optical sampling pulse through an electro-optic modulator, and the electrical domain output v out (t) can be obtained through a photodetector. Considering the case of small-signal modulation, the effects of low-pass filtering and demultiplexing can be represented by H OE (t). Without considering the direct current, the relationship between the electrical domain output signal and the signal to be sampled can be expressed as:

[0009] vout H(t) = OE H(t) * v in (t) · i(t). (1.1)

[0010] Where, v in (t) is the signal to be sampled, and i(t) is the electro - spectral equivalent sampling pulse. Equation (1.1) indicates that the electro - domain output signal can be mathematically understood as the result of directly sampling the signal to be sampled by the electro - spectral equivalent sampling pulse. Taking the Fourier transform of Equation (1.1) can obtain the relationship between the electro - spectrum of the optical sampling pulse and the transfer function, as shown in Equation (1.2):

[0011]

[0012] Where, H OE (f) is a fixed function, denotes the Fourier transform, and * denotes convolution. Since H OE (f) has no influence on the bandwidth of the optical receiver, Equation (1.2) indicates that the electro - spectrum of the optical sampling pulse directly determines the system bandwidth of the optical receiver. Therefore, by directly designing the electro - spectral response of the optical sampling pulse and then inversely deriving the spectral design based on the convolution relationship between the spectrum and the electro - spectrum, a flatter electro - spectral response can be obtained, thereby expanding the sampling bandwidth of the optical receiver. Next, we analyze the convolution relationship between the spectrum and the electro - spectrum. The optical sampling pulse is an optical frequency comb with a frequency interval of f m , a carrier frequency of f c , and an order of n in the optical domain. The convolution relationship between the spectrum and the electro - spectrum can be expressed by Equation (1.3):

[0013]

[0014] Based on Equation (1.3), we can give the specific constraint relationship between the spectrum and the electro - spectrum of the optical sampling pulse, and optimize the design of the electro - spectrum with this, obtaining the optimization problem shown in Equation (1.4):

[0015] min|I 0 (f) - min(I 0 (f), I 1 (f), I 2 (f),..., I n (f))|, (1.4)

[0016] The technical solution of the present invention is as follows:

[0017] The present invention provides a method for designing an optical sampling pulse and expanding the sampling bandwidth of a square - detection - type optical receiver, characterized in that the method includes the following stages:

[0018] - Determine the constraint relationship between the optical comb and the electro - comb of the optical sampling pulse and the electro - spectral optimization problem

[0019] Obtain the number M of the phase-locked combs of the optical sampling pulse spectrum, and calculate the corresponding number of phase-locked comb lines of the electrical spectrum;

[0020] Determine the constraint relationship between the optical comb and the electrical comb of the optical sampling pulse based on the convolution effect of the spectrum during the optoelectronic conversion process;

[0021] Determine the optimization problem required to obtain a flat electrical comb, and establish an objective function and constraint conditions;

[0022] - Solve the electrical spectrum optimization problem and determine the corresponding spectral design

[0023] Solve the optimization problem for different target electrical comb line numbers, and obtain the optimal electrical spectrum design;

[0024] Combine the number of electrical comb lines and the flatness requirement to screen the optimal electrical spectrum scheme;

[0025] Based on the optoelectronic conversion relationship, inversely deduce the spectral characteristics that meet the requirements of the optimal electrical spectrum design;

[0026] Adjust the spectral characteristics of the optical sampling pulse to conform to the theoretical design scheme.

[0027] The optical sampling pulse design and sampling bandwidth expansion method of the square detection type optical receiver are not limited by the modulator type and the modulator driving radio frequency.

[0028] The implementation methods of the described spectral design include, but are not limited to, regulating the modulation depth m and bias voltage θ of the modulator; using methods such as unequal-length interferometers and optical filtering.

[0029] The above steps are described in detail below:

[0030] - Determine the constraint relationship between the optical comb and the electrical comb of the optical sampling pulse and the electrical spectrum optimization problem

[0031] S1. Determine the sampling rate NF of the optical receiver s and the single-channel sampling rate F s . Obtain the optical comb frequency interval of the optical sampling pulse to make it consistent with F s , obtain the number M of the phase-locked comb lines of the optical sampling pulse spectrum, and calculate the corresponding number of phase-locked comb lines of the electrical spectrum according to Equation (1.3);

[0032] S2. In the square detection type optical receiver, the optical sampling pulse is an optical frequency comb with a frequency interval of f m , a carrier frequency of f c , and an order of n in the optical domain. Due to the convolution relationship between the spectrum and the electrical spectrum, this convolution relationship can be described by Equation (1.3), and the constraint conditions between the optical comb and the electrical comb are clarified.

[0033] S3. Determine the optimization problem of electro-comb flattening. According to the optoelectronic convolution constraint given by Equation (1.3), the amplitude of the zeroth-order electro-comb must be the largest. Therefore, the electro-comb flattening optimization problem can be mathematically described by Equation (1.4) to construct the objective function and constraint conditions.

[0034] - Solve the electro-spectrum optimization problem and determine the corresponding spectral design

[0035] S1. Solve the optimization problem defined by Equation (1.4) to determine the number of electro-combs n to be optimized, and when optimizing n electro-combs, make its flattening reach the optimal. Here, the value of n is between 0 - M;

[0036] S2. Combine the system's requirement for the sampling bandwidth, and comprehensively balance the number of electro-combs and flattening on the premise of ensuring the electro-comb flattening, and select the optimal electro-comb optimization number;

[0037] S3. Based on the optimal solution of the electro-spectrum optimization design and the optoelectronic conversion relationship described by Equation (1.4), inversely deduce the required spectral design to determine the amplitude distribution of each order of optical comb;

[0038] S4. Adjust the spectral parameters to make them meet the theoretical design requirements, thereby generating an optical sampling pulse that conforms to the optimization scheme and realizing the construction of the optical sampling pulse module.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] 1. The present invention is based on the precise control of the amplitude of the optical sampling pulse optical comb to obtain electro-comb components with smaller power differences, thereby realizing a flatter electro-spectrum response and effectively expanding the sampling bandwidth of the optical receiver.

[0041] 2. The present invention can optimize the electro-spectrum flattening by adjusting the amplitude of the optical sampling pulse optical comb, without introducing additional optical devices, without increasing the system complexity, and has high engineering feasibility.

[0042] 3. The bandwidth of the optical sampling pulse designed by the present invention is only limited by the number of optical combs. When the bandwidth requirement of the square-law detection optical receiver further increases, only by increasing the optical comb frequency of the optical sampling pulse can the electro-spectrum bandwidth be synchronously expanded, and it has good scalability.

[0043] 4. The present invention is applicable to various square-law detection optical receiver architectures, including but not limited to photon analog-to-digital conversion systems, optical frequency measurement, microwave photon radars, etc., and can provide a reliable technical solution for future ultra-wideband and large-scale integrated optical receivers. Brief Description of the Drawings

[0044] Figure 1 It is the overall architecture diagram of the square-law detection optical receiver embodiment to which the method of the present invention is applied;

[0045] Figure 2 Electrical spectrum design and parameter setting of the cascaded dual-parallel modulator proposed by the present invention. (a) represents the frequency setting of two dual-parallel modulators, (b) represents the electrical spectrum design of each dual-parallel modulator, (c) represents the electrical spectrum interaction relationship between two balanced modulators, and (d) represents the electrical spectrum response of the cascaded dual-parallel modulator.

[0046] Figure 3 The process of generating an electrical comb from an optical comb based on spectral convolution with a dual-parallel modulator as an example proposed by the present invention, where (a) represents the corresponding optimized electrical spectrum diagram, (b) represents the process of generating the zeroth-order electrical comb by convolving the corresponding optical comb, (c) represents the process of generating the first-order electrical comb by convolving the corresponding optical comb; (d) represents the process of generating the second-order electrical comb by convolving the corresponding optical comb.

[0047] Figure 4 The improvement effect on the flatness of the sampling pulse electrical comb in an optical receiver in the simulation of a specific embodiment of the present invention. (a) and (b) are the optical spectrum and electrical spectrum of an optical receiver system using a traditional optical sampling pulse, and (c) and (d) are the optical spectrum and electrical spectrum of an optical receiver system using the optical receiver system optimized based on spectral convolution. Detailed implementation mode

[0048] A specific embodiment of the present invention is given below in conjunction with the accompanying drawings. The optical sampling pulse source module of this embodiment consists of two cascaded dual-parallel modulators. Based on the technical solution of the present invention, detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0049] This embodiment adopts the Figure 1 shown square detection type optical receiver architecture, including an optical sampling pulse generation source 1, a signal to be sampled emission source 2, a photon sampling gate 3, a demultiplexer array 4, a photodetector array 5, an electronic analog-to-digital converter array 6, and a data integration and processing module 7. The optical sampling pulse generation source 1 consists of two cascaded dual-parallel modulators DPMZM, and its output end is connected to the second input end of the photon sampling gate 3. The output end of the signal to be sampled source 2 is connected to the first input end of the photon sampling gate 3. The output end of the photon sampling gate 3 is connected to the input end of the demultiplexer array 4. The N output ends of the demultiplexer 4 are connected to the input ends of the respective unit modules of the photodetector array 5. The N output ends of the photodetector array are connected to the input ends of the N electronic analog-to-digital converters in the electronic analog-to-digital converter array 6. The N output ends of the electronic analog-to-digital converters in the electronic analog-to-digital converter array are connected to the N input ends of the data integration and processing module.

[0050] The optical sampling pulse design and sampling bandwidth expansion method of the above-mentioned square-law detection optical receiver specifically include the following stages:

[0051] - Determine the constraint relationship between the optical sampling pulse optical comb and the electrical comb and the electrical spectrum optimization problem

[0052] S1. Determine the sampling rate NF of the optical receiver s and the single-channel sampling rate F s . Obtain the optical comb frequency interval of the optical sampling pulse, which is consistent with the single-channel sampling rate F s . In this example, the optical sampling pulse source module is a cascaded dual-parallel modulator. First, analyze a single dual-parallel modulator. The number of phase-locked comb lines in the optical sampling pulse spectrum is 5. According to Equation (1.3), the corresponding number of phase-locked comb lines in the electrical spectrum is 5. In the cascaded case, the number of comb lines of the optical comb and the electrical comb is the product of that of a single modulator. The number of phase-locked comb lines in the optical sampling pulse spectrum of the cascaded dual-parallel modulator is 25, and the corresponding number of phase-locked comb lines in the electrical spectrum is 25;

[0053] S2. Give the detailed constraints of Equation (1.3) under the dual-parallel modulator. The relationship between its optical spectrum E pulse (f) and electrical spectrum I pulse (f) is shown in Equation (1.5):

[0054]

[0055] where, I 0 (f) to I 4 (f) represent the 0th to 4th order electrical combs, and E 0 (f) to E 2 (f) represent the 0th to 2nd order optical combs. Subsequently, analyze the interaction between the two modulators in the electrical spectrum and analyze the correspondence between the optical comb and the electrical comb of each modulator.

[0056] S3. Determine the optimization problem for obtaining a flat electrical comb. Since the constraint relationship between the electrical comb and the optical comb is given by Equation (1.5), the amplitude of the 0th order electrical comb is necessarily the largest. The optimization problem for the flatness of the electrical comb can be given by Equation (1.6);

[0057] min|I 0 (f)-min(I 0 (f),I 1 (f),I 2 (f),I 3 (f),I 4 (f))|,(1.5)

[0058] where, I 0 (f) to I 4 (f) represent the 0th to 4th order electrical combs.

[0059] -Solve the electro-spectrum optimization problem and determine the corresponding spectral design

[0060] S1. Solve the optimization problem given by Equation (1.5), and find the corresponding optimal electro-spectrum and flatness when the number of target optimized electro-combs is 5, 4, and 3 respectively. When E 1 (f) = 4 / 3E 0 (f), E 2 (f) = 8 / 3E 0 (f), there is I 0 (f) = 1.375I 1 (f) = 2.64I 2 (f) = 2.64I 3 (f) = 2.64I 4 (f), at this time I 0 (f) to I 4 (f) the power difference is 8.4 dB. This indicates that when the total number of optical combs is 5, that is, in the case of using a dual-parallel modulator, it is difficult to use the generated 5 phase-locked electro-combs simultaneously. By reducing the number of target roots to be optimized, when E 1 (f) = 1 / 2E 0 (f), E 2 (f) = 3 / 4E 0 (f), I 0 (f) = 1.5I 1 (f) = 1.5I 2 (f), the power difference between the three electro-combs is 3.5 dB. Considering the system's requirement for the sampling bandwidth, comprehensively considering the number of electro-combs and flatness, select the number of electro-combs to be optimized as 3 as the optimal electro-comb of a single dual-parallel modulator;

[0061] S2. Further, analyze the cascaded dual-parallel modulator, Figure 2 (a) shows the frequency setting of the cascaded dual-parallel modulator, and the frequency settings of the two dual-parallel modulators are in a 5-fold relationship. By analogy, regardless of the number of spectral comb lines, the method of the present invention can be used to give the optimization problem between the electro-spectrum comb lines and the constraints under the corresponding optoelectronic convolution. Figure 2 (b) shows the corresponding electro-spectrum design. For the dual-parallel modulator with an input frequency of the first harmonic, the electro-spectrum satisfies I b,0 (f) = 1.5I b,1 (f) = 1.5I b,2 (f), for the dual-parallel modulator with an input frequency of the fifth harmonic, the electro-spectrum satisfies I a,0 (f) / 5 = I a,1 (f) / 4 = I a,2 (f) / 3 = I a,3 (f) / 2 = Ia,4 (f), Figure 2 (c) and (d) show the process of generating the electrical spectrum by the cascaded dual-parallel modulator and the final electrical spectrum, and the flatness between the first 11 frequency combs is 3.5 dB.

[0062] S3. Based on the optimal electrical spectrum design determined in the optical sampling pulse electrical spectrum design stage and the conversion relationship between the optical comb and the electrical comb given by Equation (1.5), the corresponding spectral design is given. For the dual-parallel modulator with an input frequency of the fundamental frequency, the electrical spectrum satisfies I b,0 (f) = 1.5I b,1 (f) = 1.5I b,2 (f), and its corresponding spectrum satisfies E 1 (f) = 1 / 2E 0 (f), E 2 (f) = 3 / 4E 0 (f); for the dual-parallel modulator with an input frequency of the fifth harmonic frequency, its corresponding spectrum satisfies E 1 (f) = E 0 (f) = E 2 (f), Figure 3 Taking the dual-parallel modulator with an input frequency of the fundamental frequency as an example, the process of generating an electrical comb from an optical comb based on spectral convolution is shown. Figure 3 (a) shows the corresponding optimized electrical spectrum; Figure 3 (b) shows the process of generating the zeroth-order electrical comb by convolving the corresponding optical comb, as shown by I 0 (f) in Equation (1.5); Figure 3 (c) shows the process of generating the first-order electrical comb by convolving the corresponding optical comb, as shown by I 1 (f) in Equation (1.5). The generation processes of the remaining electrical combs are the same as the above.

[0063] S4. Determine that the modulator architecture for implementing the optical sampling pulse is the cascaded dual-parallel modulator. Combining the spectral output expression of the modulator, calculate the modulation depth m and the bias voltage θ for achieving the target spectral design. For the dual-parallel modulator with an input frequency of the fundamental frequency, the electrical spectrum satisfies I b,0 (f) = 1.5I b,1 (f) = 1.5I b,2 (f), and its corresponding spectrum satisfies E 1 (f) = 1 / 2E 0 (f), E 2 (f) = 3 / 4E 0 (f), and its modulation depth and bias voltage satisfy Equation (1.7)

[0064]

[0065] For a double-parallel modulator with an input frequency of five times the frequency, the electrical spectrum satisfies I a,0 (f) / 5 = I a,1 (f) / 4 = I a,2 (f) / 3 = I a,3 (f) / 2 = I a,4 (f), and its modulation depth and bias voltage satisfy Equation (1.8)

[0066]

[0067] In the above process, the basic architecture settings of the receiver based on the optical sampling pulse are retained. According to the proposed optoelectronic convolution relationship, the optical comb amplitude of the optical sampling pulse is controlled to obtain more electrical combs with small power differences, so as to achieve a more flat electrical spectrum response. Experiments show that the present invention can expand the sampling bandwidth of the optical receiver without adding additional devices, without increasing the system complexity, and the bandwidth of the method proposed by the present invention is only limited by the number of optical combs. When the bandwidth requirement of the square detection type optical receiver continues to increase, only the optical comb frequency of the optical sampling pulse needs to be increased, and the electrical spectrum bandwidth based on the method proposed by the present invention also increases accordingly. The present invention can provide a more reliable technical solution for the future realization of large-scale integrated optical receivers with ultra-large bandwidth. Compared with the optical sampling pulse designed without using the method proposed by the present invention, the simulation results are as Figure 4 shown. Figure 4 (a) and (b) are the optical spectrum and electrical spectrum of the optical receiver system using the traditional optical sampling pulse, Figure 4 (c) and (d) are the optical spectrum and electrical spectrum of the optical receiver system using the optical receiver based on the present invention. The traditional design shows an envelope drop, and the flatness deviation reaches 4.6 dB at the 10th comb line. In contrast, the proposed design based on spectral convolution ensures that the 5th to 10th comb lines in the electrical domain have equal amplitudes, which are 3.5 dB lower than the 0th comb line. Our method reduces the difference between the 10th comb line and the 0th comb line by 1.1 dB. Therefore, it is obvious that the proposed design generates more available comb lines in the electrical domain and expands the bandwidth of the system.

Claims

1. A method for designing optical sampling pulses and extending sampling bandwidth suitable for square detection optical receivers, characterized in that: The steps include: Step 1. Determine the convolution constraint relationship between the optical sampling pulse light comb and the electric comb: obtain the number of optical sampling pulse spectrum phase-locked comb lines M, and establish the optical sampling pulse light comb E based on the convolution effect of the spectrum and the electric spectrum in the photoelectric conversion process. pulse (f) With electric comb I pulse The convolution constraint relationship between (f) is as follows: Among them, I n (f) represents the nth order electric comb, E k-N (f) represents the kNth order optical comb, f m represents the frequency interval of the optical comb, and N represents the total order of the optical comb. Step 2. Construct the optimization problem that needs to be satisfied by the flat electric comb of the electric spectrum: According to the convolution relationship, the electric spectrum optimization model is constructed with minimizing the difference in the electric comb amplitude as the objective function, as follows: min|I0(f)-min(I0(f),I1(f),I2(f),...,I n (f))|; Among them, I n (f) represents the nth-order electric comb; Step 3. Solve the spectrum optimization problem and inversely deduce the spectrum design; Solving the electrical spectrum optimization model according to the number of electrical combs optimized for different objectives; Select the optimal electric spectrum design scheme based on the number of electric combs and flatness requirements; Based on the convolution relationship, the optical comb amplitude distribution corresponding to the optimal electric comb is inferred, and the modulation parameters of the optical sampling pulse are adjusted to make the spectral characteristics meet the design requirements.

2. The optical sampling pulse design and sampling bandwidth extension method for a square detection type optical receiver according to claim 1, characterized in that: The generation module of the optical sampling pulse includes modulators such as a single or cascaded multiple intensity modulators, dual parallel modulators, etc.

3. The optical sampling pulse design and sampling bandwidth extension method for a square detection type optical receiver according to claim 1, characterized in that: The spectrum design of the regulated light sampling pulse is achieved by: Adjusting the modulation depth m and bias voltage θ of the modulator; Unequal length interferometers are used to adjust the phase consistency of the optical comb, or optical filters are used to suppress optical comb components in non-target frequency bands.

4. The optical sampling pulse design and sampling bandwidth extension method for a square detection type optical receiver according to claim 1, characterized in that: The square detection type optical receiver comprises a time-division channel interleaved photon analog-to-digital converter, an optical frequency measurement system or a microwave photon radar.

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