A terahertz signal generation system and method based on space optical radio frequency technology

Abstract

This invention discloses a terahertz signal generation system and method based on space-based optical radio frequency technology, comprising an optical comb generation module, an optical carrier frequency selection and modulation module, a transmission module, and a photoelectric conversion module arranged sequentially. The optical comb generation module generates an optical frequency comb. The optical carrier frequency selection and modulation module selects at least two optical carriers from the optical frequency comb and modulates the optical carriers with radio frequency signals to obtain multiple optical signals. The invention utilizes space-based optical radio frequency technology to achieve the generation and transmission of ultra-wideband terahertz signals, overcoming the bandwidth limitations of traditional electronic technology and the problem of excessive loss of terahertz signals during long-distance transmission. Optical injection locking technology is used to suppress spurious signals generated during optical domain signal processing. Furthermore, the reconfigurable generation of terahertz signals can be achieved through the joint control of the local oscillator signal and dual lasers, realizing the generation and transmission of high-speed, stable, and low-spurious broadband terahertz communication signals.

Description

Technical Field

[0001] This invention belongs to the field of terahertz communication and relates to the generation and transmission of terahertz signals. Specifically, it is a terahertz signal generation system and method based on space optical radio frequency technology. Background Technology

[0002] With the rapid development of 6G technology and emerging applications such as ultra-high-definition real-time interaction, the demand for transmission rates and spectrum resources in wireless communication systems is growing exponentially. Spectrum resources in traditional microwave bands (such as millimeter waves) are becoming increasingly scarce, making it difficult to meet future Tbps-level communication capacity requirements. Against this backdrop, the terahertz band (0.1-10 THz), due to its vast available bandwidth (covering tens of GHz to several THz), has become a key technological direction for breaking through communication capacity bottlenecks, showing broad prospects in fields such as ultra-high-speed wireless communication and high-resolution imaging. However, the generation and transmission of terahertz signals face technical challenges such as low efficiency of high-frequency devices, significant atmospheric attenuation, and complex multipath effects, necessitating the exploration of efficient, stable, and scalable solutions.

[0003] Currently, terahertz signal generation technologies are mainly divided into two categories: electronic mixing schemes and photonics-assisted schemes. The former has advantages in output power and bandwidth due to mature semiconductor processes, while the latter generates signals through photonic methods such as optical heterodyne and optical frequency combs. It has the potential to generate signals with low phase noise, high spectral purity, and seamless integration with optical networks, laying the foundation for building an integrated "optical-terahertz" communication architecture.

[0004] Free-Space Optical Communication (FSO), a wireless communication technology that uses lasers as a carrier to transmit information through free space, combines the high bandwidth advantage of fiber optic communication with the flexible deployment characteristics of wireless communication, making it particularly suitable for high-speed mobile, temporary network deployment, and complex electromagnetic environments. Compared to traditional radio frequency (RF) communication, FSO technology has significant advantages such as strong resistance to electromagnetic interference, unlicensed spectrum, and high channel capacity; however, its performance is easily affected by atmospheric turbulence and weather conditions. Combining terahertz signals with FSO technology can fully leverage the high-speed potential of the terahertz band and the anti-interference characteristics of FSO, but the efficient coupling of terahertz signals and optical carriers, as well as long-distance transmission, need to be addressed. Therefore, a method for generating terahertz signals based on FSO using space-based optical carrier RF technology is urgently needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a terahertz signal generation system and method based on space optical radio frequency technology, in order to solve the technical problems of excessive loss during long-distance transmission and the generation of spurious signals during optical domain signal processing in the combination of terahertz signals and space optical communication technology.

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

[0007] On the one hand, a terahertz signal generation system based on space optical radio frequency technology includes an optical comb generation module, an optical carrier frequency selection and modulation module, a transmission module and a photoelectric conversion module arranged sequentially;

[0008] The optical comb generation module is used to generate an optical frequency comb;

[0009] The optical carrier frequency selection and modulation module is used to select at least two optical carriers from the optical frequency comb and modulate the optical carriers with radio frequency signals to obtain multiple optical signals.

[0010] The transmission module is used to synthesize the obtained multi-channel optical signals and transmit them to the photoelectric conversion module;

[0011] The photoelectric conversion module is used to convert the received multi-channel optical signals into terahertz signals.

[0012] The optical comb generation module includes a first laser source, a MAZ modulator, a first erbium-doped fiber amplifier, and a dense wavelength division multiplexer arranged in sequence.

[0013] The stable continuous laser light generated by the No. 1 laser source is used as the seed light.

[0014] The modulator generates equally spaced phase-locked sidebands around the seed light through electro-optic modulation, thus obtaining the prototype of an optical frequency comb.

[0015] The first erbium-doped fiber amplifier amplifies the power of the prototype optical frequency comb to obtain the amplified optical frequency comb.

[0016] The dense wavelength division multiplexer performs spectral shaping and filtering on the amplified optical signal and outputs an optical frequency comb.

[0017] The optical carrier frequency selection and modulation module includes a first DP-MZM modulator and a second DP-MZM modulator connected in parallel with the dense wavelength division multiplexer. A first optical circulator and a third DP-MZM modulator are sequentially connected to the first DP-MZM modulator. A second optical circulator is connected to the second DP-MZM modulator, and the third DP-MZM modulator and the second optical circulator are connected to a coupler. A second laser is connected to the first optical circulator, and a third laser is connected to the second optical circulator.

[0018] The dense wavelength division multiplexer is used to filter out multiple specific optical carriers from the input optical frequency comb; two of the carriers are respectively guided to a first DP-MZM modulator and a second DP-MZM modulator connected in parallel for preliminary radio frequency modulation.

[0019] The output of the first DP-MZM is combined with the optical carrier injected by the second laser after passing through the first optical circulator, and then sent to the third DP-MZM for secondary or higher-order modulation. The resulting modulated signal is then output to the coupler.

[0020] The output of the second DP-MZM is combined and modulated with the optical carrier injected by the third laser after passing through the second optical circulator, and the resulting modulated signal is output to the coupler.

[0021] The coupler is used to couple two modulated signals to obtain multiple optical signals.

[0022] The transmission module includes a second erbium-doped fiber amplifier connected to a coupler, and a first optical antenna and a second optical antenna are sequentially mounted on the second erbium-doped fiber amplifier.

[0023] The second erbium-doped fiber amplifier is used to boost the power of the coupled output multiple optical signals to obtain amplified optical signals.

[0024] The first optical antenna converts the amplified optical signal into a collimated beam and transmits it into free space.

[0025] The second optical antenna is used to capture and receive the collimated beam and transmit it to the photoelectric conversion module.

[0026] The photoelectric conversion module includes a third erbium-doped fiber amplifier connected to the second optical antenna. A single-carrier photodetector and a terahertz antenna are connected in sequence to the third erbium-doped fiber amplifier.

[0027] The third erbium-doped fiber amplifier is used to perform power compensation on the aligned beam to obtain the amplified optical signal.

[0028] Single-carrier photodetectors are used to convert amplified optical signals into electrical signals in the terahertz frequency band through the photoelectric effect.

[0029] The terahertz antenna couples electrical signals in the terahertz frequency band into free space, radiating terahertz signals.

[0030] On the other hand, a terahertz signal generation method based on space-based optical radio frequency technology, based on the terahertz signal generation system based on space-based optical radio frequency technology, includes the following steps:

[0031] Step one: Laser source number one outputs the optical signal The signal is transmitted to the Maximizer modulator, which uses the input local oscillator signal. Generate optical signals in the form of a four-line optical comb The signal is then input to the first erbium-doped fiber amplifier for amplification. After amplification, the optical signal is split into optical signals by a dense wavelength division multiplexer (DWDM). and The two are then transmitted to the No. 1 DP-MZM modulator and the No. 2 DP-MZM modulator in the optical carrier frequency selection and modulation module, respectively.

[0032] (1)

[0033] (2)

[0034] (3)

[0035] (4)

[0036] (5)

[0037] in:

[0038] E 0 represents the electric field amplitude of the output optical signal from laser source number one;

[0039] The frequency of the output optical signal from laser source number one;

[0040] V Lo1 The amplitude of the No. 1 local oscillator signal;

[0041] V Lo2 The amplitude of the second local oscillator signal;

[0042] The frequency of the No. 1 local oscillator signal;

[0043] m is the modulation index;

[0044] Represents the expansion coefficients of a first-order Bessel function;

[0045] Represents the expansion coefficients of the second-order Bessel function;

[0046] exp represents the exponential function;

[0047] represents an imaginary number;

[0048] t represents time;

[0049] Step two, the first DP-MZM modulator and the second DP-MZM modulator are connected via the input second local oscillator signal. Carrier-suppressed single-sideband modulation is performed on the input optical signal respectively;

[0050] The first DP-MZM modulator retains the upper sideband optical signal and inputs it to input port 1 of the first circulator. From there, it is input to the second laser via port 2 of the first circulator for optical injection locking. The signal then returns from input port 2 of the first circulator to the first circulator and is output to the third DP-MZM modulator via port 3. In the third DP-MZM modulator, the communication baseband signal... After IQ baseband modulation, an optical signal is obtained. and transmit it to the coupler;

[0051] The second DP-MZM modulator retains the lower sideband optical signal and inputs it to input port 1 of the second circulator. From there, it is input to the third laser via port 2 of the second circulator for optical injection locking. The signal then returns from input port 2 of the second circulator to the second circulator and is output through port 3 of the second circulator. and transmit it to the coupler;

[0052] (6)

[0053] (7)

[0054] (8)

[0055] (9)

[0056] in:

[0057] The frequency of the second local oscillator signal;

[0058] V s The amplitude of the communication baseband signal;

[0059] The frequency of the communication baseband signal;

[0060] Let represent the amplitude of the communication signal at time t;

[0061] Step 3, the coupler will receive the optical signal. and light signal After being synthesized and output to the second erbium-doped fiber amplifier in the transmission module for optical amplification, the signal is transmitted through the spatial optical route from the first optical antenna to the second optical antenna. The second optical antenna outputs the received optical signal to the third erbium-doped fiber amplifier in the photoelectric conversion module for amplification. Finally, the signal undergoes photoelectric conversion through a single-carrier photodetector to obtain a terahertz signal. And output terahertz signals through a terahertz antenna. ;

[0062] (10).

[0063] Compared with the prior art, the beneficial technical effects of this invention are:

[0064] (I) In this invention, the generation and transmission of ultra-wideband terahertz signals are realized by using space optical radio frequency technology, which overcomes the bandwidth limitation of traditional electronic technology and the problem of excessive loss of terahertz signals during long-distance transmission. It can provide higher quality, higher bandwidth and longer distance terahertz signal generation and transmission. The optical injection locking technology is used to suppress the spurious signals generated during optical domain signal processing, which improves the spectral purity. Furthermore, the reconfigurable generation of terahertz signals can be realized by the joint control of the local oscillator signal and the dual lasers, thereby realizing the generation and transmission of high-speed, stable and low-spurious broadband terahertz communication signals.

[0065] (II) This invention performs signal processing in the optical domain using photonic methods, loads the generated signal onto a space laser carrier, transmits it over long distances via space laser, and completes the terahertz communication signal conversion at the terminal. Ultimately, it achieves the full-link fusion of terahertz signal "optical domain generation - space transmission - wireless radiation". It adopts optical domain four-line optical comb generation, IQ modulation and dense wavelength division multiplexing technology, combined with erbium-doped fiber amplifier and single-carrier photodetector, to achieve high-purity generation and efficient space transmission of terahertz signal.

[0066] (III) The present invention improves the stability and accuracy of the system by using a modulator with high symmetry and precise bias control. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the terahertz signal generation method based on space optical radio frequency technology proposed in this invention.

[0068] Figure 2 The signal obtained from the simulation in Example 1 is the four-line optical comb signal;

[0069] Figure 3 The constellation diagram obtained from the simulation in Example 2;

[0070] Figure 4 The terahertz single-tone signal obtained in Example 2 without the baseband communication signal is shown.

[0071] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0072] It should be noted that, unless otherwise specified, all components in this invention are those known in the art.

[0073] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0074] This invention provides a terahertz signal generation system based on space optical radio frequency technology, comprising an optical comb generation module, an optical carrier frequency selection and modulation module, a transmission module, and a photoelectric conversion module arranged sequentially.

[0075] The optical comb generation module is used to generate an optical frequency comb;

[0076] The optical carrier frequency selection and modulation module is used to select at least two optical carriers from the optical frequency comb and modulate the optical carriers with radio frequency signals to obtain multiple optical signals.

[0077] The transmission module is used to synthesize the obtained multi-channel optical signals and transmit them to the photoelectric conversion module;

[0078] The photoelectric conversion module is used to convert the received multiple optical signals into terahertz signals.

[0079] In the above technical solution, the generation and transmission of ultra-wideband terahertz signals are realized by using space optical radio frequency technology, which overcomes the bandwidth limitation of traditional electronic technology and the problem of excessive loss of terahertz signals during long-distance transmission. It can provide higher quality, higher bandwidth and longer distance terahertz signal generation and transmission. The optical injection locking technology is used to suppress spurious signals generated during optical domain signal processing, which improves spectral purity. Furthermore, the reconfigurable generation of terahertz signals can be realized by the joint control of local oscillator signal and dual lasers, thereby realizing high-speed, stable and low-spurious broadband terahertz communication signal generation and transmission.

[0080] The optical comb generation module includes a first laser source, a Marzon modulator, a first erbium-doped fiber amplifier (EDFA), and a dense wavelength division multiplexer (DWDM), arranged sequentially.

[0081] The stable, continuous laser light generated by laser source No. 1 is used as the seed light.

[0082] The Marzon modulator generates equally spaced phase-locked sidebands around the seed light through electro-optic modulation, thus obtaining the prototype of an optical frequency comb;

[0083] The No. 1 erbium-doped fiber amplifier amplifies the power of the prototype optical frequency comb to obtain the amplified optical frequency comb;

[0084] Dense wavelength division multiplexers perform spectral shaping and filtering on amplified optical signals and output optical frequency combs.

[0085] In the above technical solution, the stability and accuracy of the system are improved by using a modulator with high symmetry and precise bias control.

[0086] The optical carrier frequency selection and modulation module includes a first DP-MZM modulator (Dual Parallel Mach-zehnder Modulator) and a second DP-MZM modulator connected in parallel with the dense wavelength division multiplexer. A first optical circulator and a third DP-MZM modulator are sequentially connected to the first DP-MZM modulator. A second optical circulator is connected to the second DP-MZM modulator. The third DP-MZM modulator and the second optical circulator are connected to a coupler. A second laser is connected to the first optical circulator, and a third laser is connected to the second optical circulator.

[0087] Dense wavelength division multiplexers are used to filter out multiple specific optical carriers from the input optical frequency comb; two of the carriers are respectively guided to parallel DP-MZM modulator No. 1 and DP-MZM modulator No. 2 for preliminary radio frequency modulation.

[0088] The output of DP-MZM No. 1 is combined with the optical carrier injected by laser No. 2 after passing through optical circulator No. 1, and then sent to DP-MZM No. 3 for secondary or higher-order modulation. The resulting modulated optical signal is then output to the coupler.

[0089] The output of the second DP-MZM is combined and modulated with the optical carrier injected by the third laser after passing through the second optical circulator, and the resulting modulated signal is output to the coupler.

[0090] The coupler is used to couple two modulated signals to obtain multiple optical signals.

[0091] In the above technical solution, a tunable high-frequency radio frequency signal generation and modulation system based on the optical heterodyne method is constructed. By connecting a first DP-MZM modulator and a second DP-MZM modulator in parallel, and introducing a third DP-MZM modulator and an optical circulator in a cascade, the system can utilize optical carriers of different wavelengths generated by the second and third lasers to complete beat frequency and modulation within the modulator. Finally, after being combined by a coupler, a clean and stable high-frequency millimeter-wave or terahertz carrier signal is output, while baseband information is modulated onto it, thereby realizing high-capacity, interference-resistant, high-speed wireless transmission.

[0092] The transmission module includes a second erbium-doped fiber amplifier (EDFA2) connected to a coupler, on which a first optical antenna and a second optical antenna are sequentially mounted.

[0093] Erbium-doped fiber amplifier No. 2 is used to boost the power of the coupled output multiple optical signals to obtain amplified optical signals;

[0094] The No. 1 optical antenna converts the amplified optical signal into a collimated beam and transmits it into free space;

[0095] The second optical antenna is used to capture and receive the collimated beam and transmit it to the photoelectric conversion module.

[0096] In the above technical solution, the second erbium-doped fiber amplifier boosts the power of the optical signal from the coupler, giving it the energy required for long-distance transmission. Subsequently, the first and second optical antennas, arranged in sequence, form a beam-expanding and collimating system. They shape and expand the high-intensity laser output from the amplifier, effectively compressing the beam divergence angle to form a parallel beam with concentrated energy and excellent directionality, which is then emitted into free space, thereby ensuring that the optical signal can be stably and efficiently transmitted over long distances wirelessly.

[0097] The photoelectric conversion module includes an erbium-doped fiber amplifier (EDFA3) connected to the second optical antenna. A single-carrier photodetector (UTC-PD) and a terahertz antenna are connected sequentially to the erbium-doped fiber amplifier (EDFA3).

[0098] The No. 3 erbium-doped fiber amplifier is used to perform power compensation on the aligned beam to obtain the amplified optical signal.

[0099] Single-carrier photodetectors are used to convert amplified optical signals into electrical signals in the terahertz frequency band through the photoelectric effect.

[0100] Terahertz antennas couple electrical signals in the terahertz frequency band into free space, radiating terahertz signals.

[0101] In the above technical solution, the No. 3 erbium-doped fiber amplifier first amplifies the power of the received optical signal from the No. 2 optical antenna, providing a high-energy optical pump for subsequent conversion; then, this strong optical signal drives a high-performance single-carrier photodetector, which, through its unique high-speed and high-saturation characteristics, efficiently converts the optical signal directly into a high-power analog electrical signal; finally, the electrical signal is radiated by the terahertz antenna, thus completing the entire process from enhancing the optical signal to generating and emitting a high-intensity terahertz wave.

[0102] This invention also provides a method for generating terahertz signals based on space optical radio frequency technology, comprising the following steps:

[0103] Step one: Laser source number one outputs the optical signal The signal is transmitted to the Maximizer modulator, which uses the input local oscillator signal. Generate optical signals in the form of a four-line optical comb The signal is then input to the first erbium-doped fiber amplifier for amplification. After amplification, the optical signal is split into optical signals by a dense wavelength division multiplexer (DWDM). and The two are then transmitted to the No. 1 DP-MZM modulator and the No. 2 DP-MZM modulator in the optical carrier frequency selection and modulation module, respectively.

[0104] (1)

[0105] (2)

[0106] (3)

[0107] (4)

[0108] (5)

[0109] in:

[0110] E 0 represents the electric field amplitude of the output optical signal from laser source number one;

[0111] The frequency of the output optical signal from laser source number one;

[0112] V Lo1 The amplitude of the No. 1 local oscillator signal;

[0113] V Lo2 The amplitude of the second local oscillator signal;

[0114] The frequency of the No. 1 local oscillator signal;

[0115] m It is the modulation index;

[0116] Represents the expansion coefficients of a first-order Bessel function;

[0117] Represents the expansion coefficients of the second-order Bessel function;

[0118] exp represents the exponential function;

[0119] represents an imaginary number;

[0120] t represents time;

[0121] Step two, the first DP-MZM modulator and the second DP-MZM modulator are connected via the input second local oscillator signal. Carrier-suppressed single-sideband modulation is performed on the input optical signal respectively;

[0122] The first DP-MZM modulator retains the upper sideband optical signal and inputs it to input port 1 of the first circulator. From there, it is input to the second laser via port 2 of the first circulator for optical injection locking. The signal then returns from input port 2 of the first circulator to the first circulator and is output to the third DP-MZM modulator via port 3. In the third DP-MZM modulator, the communication baseband signal... After IQ baseband modulation, an optical signal is obtained. and transmit it to the coupler;

[0123] The second DP-MZM modulator retains the lower sideband optical signal and inputs it to input port 1 of the second circulator. From there, it is input to the third laser via port 2 of the second circulator for optical injection locking. The signal then returns from input port 2 of the second circulator to the second circulator and is output through port 3 of the second circulator. and transmit it to the coupler;

[0124] (6)

[0125] (7)

[0126] (8)

[0127] (9)

[0128] in:

[0129] The frequency of the second local oscillator signal;

[0130] V s The amplitude of the communication baseband signal;

[0131] The frequency of the communication baseband signal;

[0132] Let represent the amplitude of the communication signal at time t;

[0133] Step 3, the coupler will receive the optical signal. and light signal After being synthesized and output to the second erbium-doped fiber amplifier in the transmission module for optical amplification, the signal is transmitted through the spatial optical route from the first optical antenna to the second optical antenna. The second optical antenna outputs the received optical signal to the third erbium-doped fiber amplifier in the photoelectric conversion module for amplification. Finally, the signal undergoes photoelectric conversion through a single-carrier photodetector to obtain a terahertz signal. And output terahertz signals through a terahertz antenna. ;

[0134] (10).

[0135] In the above technical solution, signal processing is performed in the optical domain using photonic methods, and the generated signal is loaded onto a space laser carrier. After long-distance transmission via space laser, the terahertz communication signal is converted at the terminal, ultimately achieving the full-link fusion of terahertz signal "optical domain generation - space transmission - wireless radiation". The solution employs optical domain four-line optical comb generation, IQ modulation and dense wavelength division multiplexing technology, combined with erbium-doped fiber amplifier and single-carrier photodetector, to achieve high-purity generation and efficient space transmission of terahertz signal.

[0136] Example 1:

[0137] This embodiment provides a method for generating an optical frequency comb. The selected laser source generates an optical signal with a frequency of 193.1 THz, an average power of 40 mW, and a RIN of -160 dBc / Hz. A microwave signal source generates a local oscillator transmitting a sinusoidal radio frequency signal (i.e., local oscillator signal 1) with a frequency of 40 GHz and a power of 8 dBm. The half-wave voltage of the MZM is 3.5 V, and the extinction ratio is 32 dB. The optical signal output from the MZM is amplified to 15 dBm using EDFA1. The spectrum of the output four-line optical comb is as follows. Figure 2 As shown;

[0138] Example 2:

[0139] This embodiment presents a method for generating terahertz signals based on spatial optical radio frequency technology, wherein the selection of various devices is as follows:

[0140] Laser source 1 (generating an optical signal frequency of 193.1 THz, average power of 40 mW, RIN of -160 dBc / Hz); MZM (half-wave voltage of 3.5 V, extinction ratio of 32 dB); DP-MZM (half-wave voltage set to 3.5 V, insertion loss set to 6 dB); DWDM (two-channel filter bandwidth of 40 GHz, center frequencies of 193.18 THz and 193.02 THz respectively); Optical antennas 1 and 2 (75 mm aperture, ideal path loss of 50.19 dB for a 1000 km link distance); Erbium-doped fiber amplifier 3 (EDFA3, operating in automatic gain control mode, output power set to 0 dBm); UTC-PD (responsivity of 0.6 A / W, maximum output power of -10 dBm); modulation index m according to... ( This represents the voltage amplitude of the optical signal. This can be obtained by representing the half-wave voltage of MZM;

[0141] Local oscillator (LO) signal source 1 generates a 40 GHz, 12 dBm RF signal (LO1). LO1 is passed through a Markov millisecond (MZM) modulator to generate a four-line optical comb, which is then transmitted to DP-MZM modulators 1 and 2 via an erbium-doped fiber amplifier and a dense wavelength division multiplexer. LO2 signal source 2 generates a 30 GHz, 12 dBm RF signal (LO2). DP-MZM modulators 1 and 2 modulate the four-line optical comb using LO2, and perform optical injection locking using lasers 2 and 3, respectively. A 16 QAM baseband communication signal (baseband frequency, 0 dBm power) is then used to modulate the optical signal modulated by DP-MZM modulator 1. After passing through a coupler, the output optical signal constellation diagram (e.g., [image not provided]) is simulated using VPI Photonics optical simulation software. Figure 3 However, when a 16QAM baseband communication signal is not used, the terahertz single-tone signal obtained by simulation using the optical simulation software VPI Photonics without a baseband communication signal is as follows: Figure 4 The photoelectric conversion module then converts the optical signal into a terahertz signal with a center frequency of 220 GHz and a communication bandwidth of 4 GHz.

Claims

1. A terahertz signal generation system based on spatial optical carrier radio frequency technology, characterized in that, It includes, in sequence, an optical comb generation module, an optical carrier frequency selection and modulation module, a transmission module, and a photoelectric conversion module; The optical comb generation module is used to generate an optical frequency comb; The optical carrier frequency selection and modulation module is used to select at least two optical carriers from the optical frequency comb and modulate the optical carriers with radio frequency signals to obtain multiple optical signals. The transmission module is used to transmit the obtained multiple optical signals to the photoelectric conversion module; The photoelectric conversion module is used to convert the received multi-channel optical signals into terahertz signals; The optical comb generation module includes a first laser source, a Mach-Zen modulator, a first erbium-doped fiber amplifier, and a dense wavelength division multiplexer arranged sequentially. The stable continuous laser generated by the first laser source serves as the seed light. The Mach-Zen modulator generates equally spaced phase-locked sidebands around the seed light through electro-optic modulation, thus obtaining a prototype of the optical frequency comb. The first erbium-doped fiber amplifier amplifies the power of the prototype optical frequency comb to obtain an amplified optical frequency comb. The dense wavelength division multiplexer performs spectral shaping and filtering on the amplified optical signal to output the optical frequency comb. The optical carrier frequency selection and modulation module includes a first DP-MZM modulator, a second DP-MZM modulator, a first circulator, a second circulator, a second laser, a third laser, a third DP-MZM modulator, and a coupler. The first and second DP-MZM modulators are connected in parallel and are connected to a dense wavelength division multiplexer. The first DP-MZM modulator is sequentially connected to the first optical circulator and the third DP-MZM modulator. The second DP-MZM modulator is connected to the second optical circulator, and the third DP-MZM modulator and the second optical circulator are jointly connected to the coupler. The first optical circulator is connected to the second laser, and the second optical circulator is connected to the third laser. The dense wavelength division multiplexer (DWDM) is used to filter multiple specific optical carriers from the input optical frequency comb. Two carriers are respectively guided to a first DP-MZM modulator and a second DP-MZM modulator connected in parallel for initial radio frequency modulation. The output of the first DP-MZM is combined with the optical carrier injected by the second laser after passing through a first optical circulator, and then fed into a third DP-MZM for secondary or higher-order modulation. The resulting modulated optical signal is output to a coupler. The output of the second DP-MZM is combined and modulated with the optical carrier injected by the third laser after passing through a second optical circulator, and the resulting modulated optical signal is output to a coupler. The coupler is used to couple the two modulated optical signals to obtain multiple optical signals. The transmission module includes a second erbium-doped fiber amplifier connected to a coupler. A first optical antenna and a second optical antenna are sequentially mounted on the second erbium-doped fiber amplifier. The second erbium-doped fiber amplifier is used to boost the power of the coupled multi-channel optical signals to obtain amplified optical signals. The first optical antenna converts the amplified optical signals into a collimated beam and transmits it into free space. The second optical antenna is used to capture and receive the collimated beam and transmit it to the photoelectric conversion module.

2. The terahertz signal generation system based on the spatial optical carrier radio frequency technology according to claim 1, wherein, The photoelectric conversion module includes a third erbium-doped fiber amplifier connected to the second optical antenna, and a single-carrier photodetector and a terahertz antenna are connected in sequence to the third erbium-doped fiber amplifier. The third erbium-doped fiber amplifier is used to perform power compensation on the aligned beam to obtain the amplified optical signal. Single-carrier photodetectors are used to convert amplified optical signals into electrical signals in the terahertz frequency band through the photoelectric effect. The terahertz antenna couples electrical signals in the terahertz frequency band into free space and radiates terahertz signals.

3. A method for generating terahertz signals based on spatial optical carrier radio frequency technology, characterized in that, The terahertz signal generation system based on spatial optical radio frequency technology as described in claim 2 includes the following steps: Step one: Laser source number one outputs the optical signal The signal is transmitted to the Maximizer modulator, which uses the input local oscillator signal. Generate optical signals in the form of a four-line optical comb The signal is then input to the first erbium-doped fiber amplifier for amplification. After amplification, the optical signal is split into optical signals by a dense wavelength division multiplexer (DWDM). and The two are then transmitted to the No. 1 DP-MZM modulator and the No. 2 DP-MZM modulator in the optical carrier frequency selection and modulation module, respectively. (1) (2) 3) (4) (5) in: E 0 represents the electric field amplitude of the output optical signal from laser source number one; The frequency of the output optical signal of laser source number one; V Lo1 The amplitude of the No. 1 local oscillator signal; The frequency of the No. 1 local oscillator signal; m It is the modulation index; Represents the expansion coefficients of a first-order Bessel function; Represents the expansion coefficients of a second-order Bessel function; exp represents the exponential function; Imaginary numbers; t represents time; Step two, the first DP-MZM modulator and the second DP-MZM modulator are connected via the input second local oscillator signal. Carrier-suppressed single-sideband modulation is performed on the input optical signal respectively; The first DP-MZM modulator retains the upper sideband optical signal and inputs it to input port 1 of the first circulator. From there, it is input to the second laser via port 2 of the first circulator for optical injection locking. The signal then returns from input port 2 of the first circulator to the first circulator and is output to the third DP-MZM modulator via port 3. In the third DP-MZM modulator, the communication baseband signal... After IQ baseband modulation, an optical signal is obtained. and transmit it to the coupler; The second DP-MZM modulator retains the lower sideband optical signal and inputs it to input port 1 of the second circulator. From there, it is input to the third laser via port 2 of the second circulator for optical injection locking. The signal then returns from input port 2 of the second circulator to the second circulator and is output through port 3 of the second circulator. and transmit it to the coupler; (6) (7) (8) (9) in: V Lo2 The amplitude of the second local oscillator signal; The frequency of the second local oscillator signal; V s The amplitude of the communication baseband signal; The frequency of the communication baseband signal; Let represent the amplitude of the communication signal at time t; Step 3, the coupler will receive the optical signal. and light signal After being synthesized and output to the second erbium-doped fiber amplifier in the transmission module for optical amplification, the signal is transmitted through the spatial optical route from the first optical antenna to the second optical antenna. The second optical antenna outputs the received optical signal to the third erbium-doped fiber amplifier in the photoelectric conversion module for amplification. Finally, the signal undergoes photoelectric conversion through a single-carrier photodetector to obtain a terahertz signal. And output terahertz signals through a terahertz antenna. ; (10)。

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