Polarization-independent coherent detection photonic terahertz communication method and system

Abstract

A polarization-independent coherent detection photonic terahertz communication method and system, which relate to the technical field of terahertz communications. The method comprises: mapping into an original vector signal an original data stream to be transmitted, then subjecting the original vector signal to Alamouti coding to generate two signals, and making the two signals pass through a dual-polarization IQ modulator to produce a dual-polarized signal; coupling the dual-polarized signal with a local oscillator optical signal, and then performing optical heterodyne beating thereon to produce terahertz signals; converging the terahertz signals, and then mixing same with a radio-frequency signal to down-convert the terahertz signals, thereby obtaining intermediate-frequency signals; performing down-conversion, matched filtering and carrier phase recovery processing on the collected intermediate-frequency signals, thereby obtaining corrected signals; and on the basis of the corrected signals and by using an Alamouti-MIMO decoding method, obtaining the transmitted original data stream. By means of the method and system, low-complexity and low-cost polarization-insensitive photonics-assisted terahertz communication can be achieved.

Description

A polarization-independent coherent detection photonic terahertz communication method and system Technical Field

[0001] This invention relates to the field of terahertz communication technology, and in particular to a polarization-independent coherent detection photon terahertz communication method and system. Background Technology

[0002] In the vision and technology roadmap of 6G development, terahertz communication is widely regarded as a core component of future 6G mobile communication systems. Photonic-assisted terahertz communication systems (i.e., photonic terahertz communication systems), with their ability to seamlessly integrate fiber optic and terahertz links and their advantages of high capacity and ultra-wide bandwidth, are increasingly becoming a research focus. Photonic-assisted terahertz communication systems use optical heterodyne beat frequency generation (i.e., the coupled signal light and local oscillator light are fed together into a photodetector for beat frequency generation). The adjustable signal frequency range covers the entire terahertz band, resulting in high spectrum resource utilization. It has broad application prospects in future high-capacity communication, inter-satellite communication, and integrated space-ground communication.

[0003] However, for traditional photon-assisted terahertz communication systems, the polarization alignment between the two beams needs to be carefully considered during optical heterodyne beat frequency execution. During transmission, factors such as fiber optic transmission, mechanical stress, and temperature changes can cause polarization mismatch between the signal light and the local oscillator beam. This mismatch results in an angular deviation from the local oscillator beam direction when the signal light enters the coupler, leading to power degradation in the generated terahertz signal and thus polarization sensitivity (as shown in Figure 2(a)). In extreme cases, when the two beams are orthogonal, the terahertz signal power generated by the beat frequency is completely lost, rendering it unable to carry any useful information. Therefore, at the current communication system architecture level, it is unavoidable to use polarization controllers or polarization tracking algorithms to actively control the polarization state of the signal to align with the local oscillator beam direction, or to employ a polarization diversity optical heterodyne detection system to maintain system performance and address the polarization sensitivity problem.

[0004] While the two methods mentioned above can address the polarization sensitivity issue, the application of polarization controllers cannot guarantee long-term system stability, requiring real-time manual monitoring of the signal polarization state. This approach is not a permanent solution. Polarization tracking algorithms typically involve complex tracking processes and feedback mechanisms, significantly increasing system complexity and reducing robustness. Furthermore, polarization diversity optical heterodyne detection systems require additional optical components (such as polarization beam splitters and optical couplers), increasing system cost and reducing optical detection sensitivity. Therefore, current photon-assisted terahertz communication systems urgently need a low-complexity, cost-effective polarization-insensitive solution to improve system reliability and operability. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a polarization-independent coherent detection photonic terahertz communication method and system. Based on Alamouti coding technology and combined with the proposed Alamouti-MIMO decoding algorithm based on polarization-independent theory, this invention can achieve polarization-insensitive transmission of terahertz signals without using any active polarization control means or introducing additional optical devices. This simplifies the communication system while maintaining the long-term stability of communication performance, improving the reliability and operability of the system, thereby supporting low-complexity, low-cost polarization-insensitive photon-assisted terahertz communication.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A polarization-independent coherent detection photonic terahertz communication method proposed according to the present invention includes:

[0008] The original data stream to be transmitted is mapped into an original vector signal, and then the original vector signal is encoded by Alamouti to generate two signals. These two signals are then processed by a dual-polarization IQ modulator to generate dual-polarization signals.

[0009] After the dual-polarization signal is coupled with the local oscillator optical signal, a terahertz signal is generated by optical heterodyne beat frequency.

[0010] After the terahertz signal is converged, it is mixed with the radio frequency signal to achieve down-conversion of the terahertz signal and obtain the intermediate frequency signal.

[0011] The acquired intermediate frequency signal is down-converted, matched filtered, and carrier phase recovered to obtain the correction signal;

[0012] Based on the correction signal, the original transmitted data stream is obtained using the Alamouti-MIMO decoding method; wherein, the Alamouti-MIMO decoding method includes:

[0013] The correction signal is separated into odd and even data blocks to obtain odd block signals and even block signals. The even block signals are conjugate and then used together with the odd block signals to recover the original vector signal using the Volterra-MIMO equalization method. Finally, the original data stream is demapped to obtain the transmitted data stream.

[0014] A polarization-independent coherent detection photonic terahertz communication system includes:

[0015] The optical transmitter maps the raw data stream to be transmitted into a raw vector signal, and then the raw vector signal is encoded by Alamouti to generate two signals. These two signals are then processed by a dual-polarization IQ modulator to generate dual-polarization signals, which are then output to the optical-to-wireless conversion module.

[0016] The optical-to-wireless conversion module is used to couple the dual-polarization signal with the local oscillator optical signal and generate a terahertz signal through optical heterodyne beat frequency, and the terahertz signal is output to the terahertz wireless receiver.

[0017] A terahertz wireless receiver is used to converge terahertz signals and mix them with radio frequency signals to achieve down-conversion of the terahertz signals, obtain intermediate frequency signals, and output them to the processing module.

[0018] The processing module is used to downconvert the acquired intermediate frequency signal, perform matched filtering and carrier phase recovery to obtain a correction signal, separate the correction signal into odd and even data blocks to obtain odd block signals and even block signals, take the conjugate of the even block signals and use the Volterra-MIMO equalization method together with the odd block signals to recover the original vector signal, and demap to obtain the original data stream to be transmitted.

[0019] As a further optimization of the polarization-independent coherent detection photonic terahertz communication system described in this invention, in the optical-to-wireless conversion module, the dual-polarization signal generated based on Alamouti coding is coupled with the local oscillator signal and then generated by optical heterodyne beat frequency. The signal is then amplified by a terahertz low-noise amplifier and transmitted through a high-gain antenna, completing the conversion of light into terahertz wireless signal. Finally, the signal is transmitted to the terahertz wireless receiver via a wireless link.

[0020] As a further optimization of the polarization-independent coherent detection photonic terahertz communication system described in this invention, in the terahertz wireless receiver, the terahertz signal is converged and received by a horn antenna, then amplified by a low-noise amplifier and mixed with a frequency-doubled radio frequency signal in a terahertz mixer to achieve down-conversion of the terahertz signal to obtain an intermediate frequency signal. The intermediate frequency signal is then amplified by an electrical amplifier and input to the processing module.

[0021] As a further optimization scheme for the polarization-independent coherent detection photonic terahertz communication system described in this invention, the processing module includes a receiver signal acquisition module, a down-conversion module, a matched filter module, a carrier phase recovery module, an odd-even data separation module, an even-block signal conjugation module, a Volterra-MIMO equalization module, and a signal demapping module.

[0022] The receiver signal acquisition module is used to acquire the intermediate frequency signal amplified by the electrical amplifier;

[0023] The downconverter module is used to convert the intermediate frequency signal to baseband and output the baseband signal to the matched filter module;

[0024] The matched filtering module and carrier phase recovery module are used to perform matched filtering and carrier phase recovery on the baseband signal to obtain the corrected signal;

[0025] The odd-even data separation module is used to separate the correction signal into odd-even data blocks to obtain odd-block signals and even-block signals;

[0026] The even-block signal conjugate module is used to take the conjugate of the even-block signal and use it together with the odd-block signal as the two inputs of the Volterra-MIMO equalization module.

[0027] The Volterra-MIMO equalization module is used to recover the original vector signal using a linear equalization method. The original vector signal is then output to the signal demapping module.

[0028] The signal demapping module is used to demapping the original vector signal to obtain the original data stream to be transmitted.

[0029] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0030] (1) On the one hand, the polarization-independent coherent detection photonic terahertz communication system proposed in this invention can decode the signal and recover the original vector signal under different polarization states through the designed Alamouti-MIMO decoding algorithm.

[0031] (2) This invention simplifies the coherent detection photonic terahertz communication scheme based on polarization-independent transmission. The system transmitter only needs one set of photodetectors and no longer requires additional polarization-dependent devices (such as polarization controllers, polarization beam splitters, etc.), reducing system cost and improving receiving sensitivity. This scheme no longer needs to consider the polarization state of the system, can maintain the system's performance under long-term operation, has high stability and robustness, and can well adapt to the development of future long-distance communication systems. Attached Figure Description

[0032] Figure 1 illustrates the key modulation and demodulation process of the polarization-independent coherent detection photonic terahertz communication system based on Alamouti coding provided in this invention example.

[0033] Figure 2 is a schematic diagram of the formation principle of the polarization-sensitive problem in the traditional scheme provided by the example of the present invention and a schematic diagram of the polarization-independent implementation principle based on Alamouti encoding; wherein, (a) is a schematic diagram of the formation principle of the polarization-sensitive problem in the traditional scheme, and (b) is a schematic diagram of the polarization-independent implementation principle based on Alamouti encoding.

[0034] Figure 3 is a schematic diagram of the structure of a polarization-independent coherent detection photonic terahertz communication system based on Alamouti coding provided in the example of the present invention;

[0035] Figure 4 is a schematic diagram of the optical transmitter structure of the polarization-independent coherent detection photonic terahertz communication system provided in the example of the present invention;

[0036] Figure 5 is a schematic diagram of the algorithm flow of the DSP processing module of the polarization-independent coherent detection photonic terahertz communication system provided in the example of the present invention.

[0037] Figure 6 is a simplified structural diagram of a polarization-independent coherent detection photonic terahertz communication system based on Alamouti coding, provided by an example of the present invention.

[0038] The reference numerals in the attached figures are explained as follows: 11-Optical transmitter of a polarization-independent system based on Alamouti coding; 12-Fiber optic link; 13-Optical-to-terahertz conversion module; 21-Terahertz signal wireless receiver; 22-DSP processing module of a polarization-independent system based on Alamouti coding; 131-Optical coupler; 132-Local oscillator laser; 133-Photodetector; 134-Terahertz low-noise amplifier; 135-High-gain antenna; 211-Horn antenna; 212-Terahertz low-noise amplifier; 213-RF source; 214-Terahertz mixer; 215-Electrical amplifier.

[0039] 111 - Vector signal generation module, 112 - Alamouti encoding processing module, 113 - Dual polarization IQ modulator, 114 - Transmitter laser;

[0040] 221-Receiver signal acquisition module, 222-Down-conversion module, 223-Matched filter module, 224-Carrier phase recovery module, 225-Odd-even data separation module, 226-Even block signal conjugation module, 227-Volterra-MIMO equalization module, 228-Signal demapping module. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] The processing flow of the polarization-independent coherent detection photonic terahertz communication system based on Alamouti coding provided in this invention is shown in Figure 1. In the optical transmitter, the original data stream to be transmitted is mapped into an original vector signal using an offline Matlab program. Then, Alamouti coding is used to generate two signals carrying the same information content but different formats. These signals are subsequently processed by a dual-polarization IQ modulator (DP-IQ modulator) to generate dual-polarization signals. During coding, considering the different responses of the modulator to odd and even signals, significant inter-symbol interference (ISI) that is difficult to compensate for by the equalizer is introduced at the boundary between odd and even data blocks. Block coding is used to reduce the performance impact of ISI. The dual-polarization signals obtained by this coding and modulation method can be carried on the same optical carrier, and when projected onto the local oscillator, they can mutually compensate for performance losses, thereby solving the polarization sensitivity problem.

[0043] In the optical-to-wireless conversion module, the dual-polarization signal generated by Alamouti coding is coupled with the local oscillator signal and then generated by optical heterodyne beat frequency. The signal is amplified by the terahertz low-noise amplifier and then transmitted through the high-gain antenna to complete the conversion of light into terahertz wireless signal, which is then transmitted via wireless link.

[0044] In a terahertz wireless receiver, the divergent terahertz signal is converged and received by a horn antenna. It is then amplified by a low-noise amplifier to compensate for free-space path loss. Subsequently, it is mixed with a frequency-doubled radio frequency signal in a terahertz mixer to achieve down-conversion of the terahertz signal, yielding an intermediate frequency (IF) signal. The IF signal is then amplified by an electrical amplifier and received and acquired by a digital storage oscilloscope.

[0045] In the DSP processing module, the acquired intermediate frequency signal is first down-converted to obtain the baseband signal, and the baseband signal is subjected to matched filtering. Then, the carrier phase recovery algorithm (CPE) is used to perform frequency offset and phase compensation. Finally, the processed signal is sent to the Alamouti-MIMO decoding algorithm module designed according to the polarization-independent theory of this invention to recover the original vector signal and demap it to obtain the original transmitted data stream, and to calculate the bit error rate and other related results.

[0046] The polarization-independent photonic terahertz communication system proposed in this invention is a low-complexity, cost-effective, and polarization-insensitive solution that can maintain stable system performance for a long time without being sensitive to the polarization state, thereby improving the system's reliability and operability.

[0047] The polarization-independent photonic terahertz communication system proposed in this invention can maintain stable system performance for a long time without considering the system's polarization state, as illustrated in Figure 2(b). In traditional single-polarization systems, the signal light is affected by optical devices, temperature, etc., during transmission, resulting in polarization rotation. When incident on the coupler, it is not on the same plane as the local oscillator signal and needs to be projected onto the local oscillator signal, causing a power loss in the generated terahertz signal. Figure 2(a) shows the power changes of four different polarization states in a traditional single-polarization system after coupling with the local oscillator light at a beat frequency. However, after Alamouti encoding, the two signals carrying the same information but different forms are both projected onto the local oscillator light when coupled. As can be seen intuitively from Figure 2(b), the two sets of signals can compensate for each other's power loss.

[0048] To further enhance the credibility of the scheme, the polarization independence principle is theoretically derived next. The original vector signal, after Alamouti encoding, is converted into a dual-polarization signal by a DP-IQ modulator. Assume the original vector signal SP = [S1 S2 S3 S4……S…]i The signal E, after Alamouti encoding, carries two different polarizations (denoted as X-polarization and Y-polarization). x and E y They can be represented as E respectively. x =[S1-S2 * S3-S4 * ...], E y =[S2S1 * S4S3 * ...], for simplicity, the following will use the first two symbol blocks as examples. H = [h xx h xy h yx h yy ] represents the channel response of the optical fiber, where h xx h represents the influence coefficient between signals on X-polarization. xy h represents the influence coefficient of the X-polarized signal on the Y-polarized signal. yx h represents the influence coefficient of the Y-polarized signal on the X-polarized signal. yy The coefficient representing the influence between signals on the Y-polarized side is given. Therefore, the signal reaching the optical coupler 131 after transmission through the optical fiber can be expressed as:

[0049]

[0050] Among them, S i This represents the i-th vector signal block, where i = 1, 3, 5, ... represents odd-numbered blocks, and i = 2, 4, 6, ... represents even-numbered blocks. E x ′, E y ′ represents the signal carried on the two polarizations after being affected by polarization rotation during transmission. Alamouti encoded data pairs [S1-S2] possess inherent orthogonality. * ] and [S2S1 * It propagates simultaneously in both X and Y polarization, and '*' indicates conjugation.

[0051] When coupled with the local oscillator light, assuming the angle between the local oscillator light and the X-polarization direction of the incident signal is θ (θ∈[-90°,90°]), as shown in Figure 2(b), then after simple optical heterodyne detection with polarization diversity based on a single photodetector UTC-PD, the signals in the two polarization states will be projected onto the direction of the local oscillator light with coefficients related to the polarization rotation angle θ, thus obtaining a superimposed terahertz signal: E oc =cosθ×E x +sinθ×E y Based on this, the generated terahertz signal (i.e., E) oc The first odd block and the first even block can be represented as:

[0052]

[0053] Among them, S odd It is the odd-numbered block of the signal after projection and accumulation, S even It is the even-numbered block of the signal after projection and accumulation. 'T' indicates transpose and '×' indicates multiplication.

[0054]

[0055] As shown in the formula above, taking the conjugate of the even-numbered signal blocks and rearranging them reveals that the conjugate signal and the original vector signal exhibit a matrix transformation relationship, where H1 is the transformation matrix. Furthermore, the determinant of H1, |H1|, is found to be -|h. xx cosθ+h yx sinθ| 2 -|h xy cosθ+h yy sinθ| 2 If the result is not zero, it means that the processed signal and the original vector signal are linearly transformed, and the original vector signal can be recovered by an equalizer.

[0056] This theoretically proves the feasibility of using Alamouti coding to achieve polarization-independent transmission. Under any polarization angle θ, polarization can be achieved from the received [S] odd S even * ] T The original vector signal [S1S2] is recovered from it.

[0057] The polarization-independent transmission scheme proposed in this invention can maintain long-term stable system performance without the need for polarization control or the introduction of additional optical components. A schematic diagram of the polarization-independent coherent detection photonic terahertz communication system based on Alamouti coding is shown in Figure 3. It mainly consists of an Alamouti-coded polarization-independent system optical transmitter 11, an optical fiber link 12, an optical-to-terahertz conversion module 13, a terahertz signal wireless receiver 21, and an Alamouti-coded polarization-independent system DSP processing module 22.

[0058] The polarization-independent system optical transmitter 11 based on Alamouti coding is used to generate dual-polarization signals after Alamouti coding. The two polarizations carry signals with the same information but different forms, as shown in Figure 4. The vector signal generation module 111 generates the original first vector signal and sends it to the Alamouti coding processing module 112, which generates the second and third vector signals according to the coding rules. Since the dual-polarization modulator responds differently to odd and even symbols, significant inter-symbol interference (ISI) is introduced at the boundary between odd and even data blocks. To reduce the performance impact of ISI, the Alamouti block coding scheme is adopted, where a symbol block contains multiple symbols, and coding is performed on a block-by-block basis. The two generated vector signals are sent to the dual-polarization IQ modulator 113, which, together with the transmitting laser 114, drives the dual-polarization IQ modulator 113 to generate dual-polarization signals.

[0059] After the aforementioned dual-polarization signal is transmitted over a longer distance via fiber optic link 12, it is coupled with the local oscillator light from local oscillator laser 132 in optical-to-wireless conversion terminal 13. Subsequently, a terahertz signal is generated by beat frequency in photodetector 133, completing the conversion from light to terahertz. During this process, the signals in both polarization states are projected towards the direction of the local oscillator light. The carrier frequency of the generated terahertz signal is equal to the center frequency interval between the transmitting laser 114 and the local oscillator laser 132. The terahertz signal generated by beat frequency is then amplified by terahertz low-noise amplifier 134, transmitted through high-gain antenna 135, and received and collected by wireless receiver 21 via the wireless link.

[0060] In the wireless receiver 21, the terahertz signal received by the horn antenna 211 is first amplified by the terahertz low-noise amplifier 212 to compensate for the severe free path loss in long-distance transmission. The radio frequency signal generated by the radio frequency source 213 is frequency multiplied and then mixed with the terahertz signal in the terahertz mixer 214, down-converting it to an intermediate frequency signal. Subsequently, it is amplified by the electrical amplifier 215 and sent to the polarization-independent system DSP processing module 22 based on Alamouti coding to complete the recovery of the original vector signal and the calculation of related results such as the bit error rate. Figure 6 is a simplified structural diagram of a polarization-independent coherent detection photonic terahertz communication system based on Alamouti coding provided by an example of the present invention.

[0061] The algorithm flow of the DSP processing module of the polarization-independent coherent detection photonic terahertz communication system provided in this invention example is shown in Figure 5. First, the intermediate frequency signal amplified by the amplifier 215 is acquired by the receiver signal acquisition module 221 and down-converted to baseband by the down-conversion module 222 for subsequent processing. Then, the signal is sent to the matched filter module 223 for matched filtering, and the carrier phase recovery module 224 compensates for the frequency offset and phase noise effects during transmission. Based on the derivation process of polarization-independent theory, this invention designs an Alamouti-MIMO decoding module, which mainly includes an odd-even data separation module 225, an even-block signal conjugation module 226, a Volterra-MIMO equalization module 227, and a signal demapping module 228. The data processed by the carrier phase recovery module 224 is sent to the odd-even data separation module 225 to separate the odd-numbered block signals and even-numbered block signals. The even-numbered block signals to be processed are sent to the even-numbered block signal conjugation module 226 to obtain the conjugate, and together with the odd-numbered block signals to be processed, they are used as the input of the Volterra-MIMO equalization module 227. The Volterra-MIMO equalization module 227 utilizes the characteristic that the conjugated signal and the original vector signal have a linear relationship, and uses the odd-numbered block signal S based on a portion of the original vector signal. 2k+1 and even number of block signals S 2k+2 Training data (k = 0, 1, 2, 3, ...) is used to assist in estimating the channel response H1, and the original vector signal is recovered using a linear equalization method. Finally, the original vector signal obtained by equalization is sent to the signal demapping module 228 to obtain the original data stream transmitted by the polarization-independent system optical transmitter 11 based on Alamouti coding, and related results such as the bit error rate are calculated.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A polarization-independent coherent detection photon terahertz communication method, characterized in that, include: The original data stream to be transmitted is mapped into an original vector signal, and then the original vector signal is encoded by Alamouti to generate two signals. These two signals are then processed by a dual-polarization IQ modulator to generate dual-polarization signals. After the dual-polarization signal is coupled with the local oscillator optical signal, a terahertz signal is generated by optical heterodyne beat frequency. After the terahertz signal is converged, it is mixed with the radio frequency signal to achieve down-conversion of the terahertz signal and obtain the intermediate frequency signal. The acquired intermediate frequency signal is down-converted, matched filtered, and carrier phase recovered to obtain the correction signal; Based on the correction signal, the original transmitted data stream is obtained using the Alamouti-MIMO decoding method; wherein, the Alamouti-MIMO decoding method includes: The correction signal is separated into odd and even data blocks to obtain odd block signals and even block signals. The even block signals are conjugate and then used together with the odd block signals to recover the original vector signal using the Volterra-MIMO equalization method. Finally, the original data stream is demapped to obtain the transmitted data stream.

2. A polarization-independent coherent detection photonic terahertz communication system, characterized in that, include: The optical transmitter maps the raw data stream to be transmitted into a raw vector signal, and then the raw vector signal is encoded by Alamouti to generate two signals. These two signals are then processed by a dual-polarization IQ modulator to generate dual-polarization signals, which are then output to the optical-to-wireless conversion module. The optical-to-wireless conversion module is used to couple the dual-polarization signal with the local oscillator optical signal and generate a terahertz signal through optical heterodyne beat frequency, and the terahertz signal is output to the terahertz wireless receiver. A terahertz wireless receiver is used to converge terahertz signals and mix them with radio frequency signals to achieve down-conversion of the terahertz signals, obtain intermediate frequency signals, and output them to the processing module. The processing module is used to downconvert the acquired intermediate frequency signal, perform matched filtering and carrier phase recovery to obtain a correction signal, separate the correction signal into odd and even data blocks to obtain odd block signals and even block signals, take the conjugate of the even block signals and use the Volterra-MIMO equalization method together with the odd block signals to recover the original vector signal, and demap to obtain the original data stream to be transmitted.

3. The polarization-independent coherent detection photonic terahertz communication system according to claim 2, characterized in that, In the optical-to-wireless conversion module, the dual-polarization signal generated by Alamouti coding is coupled with the local oscillator signal and then generated by optical heterodyne beat frequency. The signal is amplified by the terahertz low-noise amplifier and then transmitted through the high-gain antenna to complete the conversion of light into terahertz wireless signal. The signal is then transmitted to the terahertz wireless receiver via a wireless link.

4. The polarization-independent coherent detection photonic terahertz communication system according to claim 2, characterized in that, In a terahertz wireless receiver, the terahertz signal is collected by a horn antenna, amplified by a low-noise amplifier, and then mixed with a frequency-doubled radio frequency signal in a terahertz mixer to achieve down-conversion of the terahertz signal to obtain an intermediate frequency (IF) signal. The IF signal is then amplified by an electrical amplifier and input to the processing module.

5. A polarization-independent coherent detection photonic terahertz communication system according to claim 2, characterized in that, The processing module includes a receiver signal acquisition module, a down-conversion module, a matched filter module, a carrier phase recovery module, an odd-even data separation module, an even-block signal conjugation module, a Volterra-MIMO equalization module, and a signal demapping module; The receiver signal acquisition module is used to acquire the intermediate frequency signal amplified by the electrical amplifier; The downconverter module is used to convert the intermediate frequency signal to baseband and output the baseband signal to the matched filter module; The matched filtering module and carrier phase recovery module are used to perform matched filtering and carrier phase recovery on the baseband signal to obtain the corrected signal; The odd-even data separation module is used to separate the correction signal into odd-even data blocks to obtain odd-block signals and even-block signals; The even-block signal conjugate module is used to take the conjugate of the even-block signal and use it together with the odd-block signal as the two inputs of the Volterra-MIMO equalization module. The Volterra-MIMO equalization module is used to recover the original vector signal using a linear equalization method. The original vector signal is then output to the signal demapping module. The signal demapping module is used to demapping the original vector signal to obtain the original data stream to be transmitted.

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