CN-122027041-A - System and method for generating high frequency multiplication radio frequency signal by subharmonic light injection locking

CN122027041ACN 122027041 ACN122027041 ACN 122027041ACN-122027041-A

Abstract

The invention relates to a system and a method for generating a high-frequency-multiplication radio frequency signal by subharmonic optical injection locking. The system for generating the high-frequency-multiplication radio frequency signal comprises a laser, a dual-polarization Mach-Zehnder modulator, a 180-degree bridge coupler, a polarization beam splitter, an external polarization beam combiner, a Fabry-Perot filter, an erbium-doped fiber amplifier, a polarization controller, a photoelectric detector, a low-phase noise amplifier, a broadband filter and an electric coupler. The system can generate radio frequency signals with high frequency and low phase noise, ensures that the phase noise of the near-frequency end of the generated radio frequency signals is low by adopting an optical injection locking mode, and realizes the generation of the low phase noise of the far-frequency end of the radio frequency signals based on the photoelectric oscillator technology. The invention can generate microwave signals with high frequency and low phase noise, and has the advantages of simple system structure and good adaptability.

Inventors

HAO PENG
ZHAO XIAOPENG
Hao tengfei
LI MING
YAO XIAOTIAN

Assignees

河北大学
中国科学院半导体研究所

Dates

Publication Date: 20260512
Application Date: 20251205

Claims (9)

1. The system for generating the high-frequency-multiplication radio frequency signal by sub-harmonic light injection locking is characterized by comprising a laser, a dual-polarization Mach-Zehnder modulator, a polarization beam splitter, a Fabry-Perot filter, an erbium-doped fiber amplifier, a polarization controller, an external polarization beam combiner, a photoelectric detector, a low-phase noise amplifier, a broadband filter and an electric coupler which are connected in sequence; The dual-polarization Mach-Zehnder modulator comprises a first branch and a second branch which respectively work in an X polarization state and a Y polarization state, and an internal polarization beam combiner which is connected at the tail ends of the two branches, wherein the first branch is internally provided with a first dual-drive Mach-Zehnder modulator connected with a first 180-degree bridge coupler, the second branch is internally provided with a second dual-drive Mach-Zehnder modulator connected with a second 180-degree bridge coupler, the first 180-degree bridge coupler is connected with an RF signal source, the first 180-degree bridge coupler is used for loading a radio frequency signal with the frequency of f in sent by the RF signal source onto an optical carrier signal modulated by the first dual-drive Mach-Zehnder modulator, the second 180-degree bridge coupler is connected with an electric coupler, and the dual-polarization Mach-Zehnder modulator is used for modulating an optical carrier signal input by a laser so as to output a modulated orthogonal optical signal containing positive and negative n-order sidebands and carrier waves; The input end of the polarization beam splitter is connected with the internal polarization beam combiner, the X-polarization state light output end of the polarization beam splitter is connected with the Fabry-Perot filter, and the Y-polarization state light output end of the polarization beam splitter is connected with the external polarization beam combiner; The optical fiber amplifier comprises a polarization beam splitter, an erbium-doped fiber amplifier, a Fabry-Perot filter, a polarization controller and an erbium-doped fiber amplifier, wherein the Fabry-Perot filter is used for filtering other optical wave signals except positive and negative n-order sidebands in an X-polarized optical signal output by the polarization beam splitter; The photoelectric detector is used for performing beat frequency and photoelectric conversion on the combined beam light signals output by the external polarization beam combiner, the X-polarization state light signals in the combined beam light signals are subjected to beat frequency and photoelectric conversion to generate radio frequency signals with the frequency of 2nf in , and the Y-polarization state light signals in the combined beam light signals are subjected to beat frequency and photoelectric conversion to generate radio frequency signals with the frequency of f oeo ; The center frequency of the broadband filter is 2nf in , the broadband filter is used for defining the frequency range of the radio frequency signal output by the low-phase noise amplifier and filtering harmonic signals of other orders in the radio frequency signal, the coupling output end of the electric coupler is used as the system output end for outputting high-frequency multiplication radio frequency signals generated by the system, the through output end of the electric coupler is connected with the second 180-degree bridge coupler and used for closing the high-frequency multiplication photoelectric oscillation loop, and the high-frequency multiplication radio frequency signals generated by the system are loaded on the Y-polarization optical carrier signals in the dual-polarization Mach-Zehnder modulator.
2. The system for generating high-frequency-multiplication radio frequency signals by sub-harmonic optical injection locking according to claim 1, wherein a first dual-drive Mach-Zehnder modulator working in an X polarization state is connected to a first branch of the dual-polarization Mach-Zehnder modulator, a second dual-drive Mach-Zehnder modulator working in a Y polarization state is connected to a second branch, the two branches work in an orthogonal polarization state, the tail end of the first branch is connected to an X polarization state optical input end of an internal polarization beam combiner, and the tail end of the second branch is connected to a Y polarization state optical input end of the internal polarization beam combiner.
3. The system for generating a high frequency multiplied radio frequency signal with subharmonic optical injection locking of claim 1, wherein the Gao Beipin opto-electronic oscillation loop comprises a laser, a second leg in a dual polarization mach-zehnder modulator, a second 180 ° bridge coupler, a polarizing beam splitter, an external polarization beam combiner, a photodetector, a low phase noise amplifier, a wideband filter, and an electrical coupler.
4. The system for generating the high-frequency-multiplication radio frequency signal by sub-harmonic light injection locking is characterized by further comprising a single-drive Mach-Zehnder modulator on the basis of the system for generating the high-frequency-multiplication radio frequency signal by sub-harmonic light injection locking according to claim 1, wherein the single-drive Mach-Zehnder modulator is arranged between a polarization beam splitter and a Fabry-Perot filter, namely, an X-polarization state light output end of the polarization beam splitter is connected with an input end of the single-drive Mach-Zehnder modulator, an output end of the single-drive Mach-Zehnder modulator is connected with the Fabry-Perot filter, a radio frequency input end of the single-drive Mach-Zehnder modulator is connected with an RF signal source, and the single-drive Mach-Zehnder modulator is used for generating a higher-order sideband light signal in a cascading mode.
5. The system of claim 4, wherein a first dual-drive Mach-Zehnder modulator operating in an X-polarization state is connected to a first branch of the dual-polarization Mach-Zehnder modulator, a second dual-drive Mach-Zehnder modulator operating in a Y-polarization state is connected to a second branch of the dual-polarization Mach-Zehnder modulator, the two branches are operating in orthogonal polarization states, and an end of the first branch is connected to an X-polarization optical input of the internal polarization combiner, and an end of the second branch is connected to a Y-polarization optical input of the internal polarization combiner.
6. The system for generating a high frequency multiplied radio frequency signal with subharmonic optical injection locking of claim 4, wherein the Gao Beipin opto-electronic oscillation loop comprises a laser, a second leg in a dual polarization mach-zehnder modulator, a second 180 ° bridge coupler, a polarizing beam splitter, an external polarization beam combiner, a photodetector, a low phase noise amplifier, a wideband filter, and an electrical coupler.
7. A method for generating a high frequency multiplication radio frequency signal by subharmonic optical injection locking, comprising the steps of: s1, setting a system for generating a high frequency multiplication radio frequency signal by subharmonic optical injection locking according to any one of claims 1-3; S2, the laser sends out linearly polarized optical carrier signals to a first branch and a second branch of the dual-polarization Mach-Zehnder modulator; s3, the RF signal source injects a radio frequency signal with the frequency of f in into a first dual-drive Mach-Zehnder modulator in a first branch through a first 180-degree bridge coupler, the first dual-drive Mach-Zehnder modulator modulates an optical carrier signal passing through the first branch in an X polarization state and generates an n-order sideband in the X polarization state; S4, the dual-polarization Mach-Zehnder modulator synthesizes the orthogonal optical signals modulated by the X polarization state and the Y polarization state into modulated orthogonal optical signals containing positive and negative n-order sidebands and carriers through an internal polarization beam combiner, and then outputs the modulated orthogonal optical signals to the polarization beam splitter; S5, carrying out orthogonal separation on an X polarization state and a Y polarization state on the input modulated orthogonal optical signals by a polarization beam splitter, outputting optical signals in the Y polarization state to an external polarization beam combiner, and outputting optical signals in the X polarization state containing positive and negative n-order sidebands and carrier waves to a Fabry-Perot filter; s6, filtering other light wave signals in the X polarization state light signals by using a Fabry-Perot filter, retaining the light signals only containing positive and negative n-order sidebands, and outputting the light signals to an erbium-doped optical fiber amplifier; S7, the external polarization beam combiner combines the X-polarized light signals output by the polarization controller and the Y-polarized light signals output by the polarization beam splitter and outputs the combined light signals to the photoelectric detector for beat frequency and photoelectric conversion operation, wherein the X-polarized light signals in the combined light signals are subjected to beat frequency and photoelectric conversion to generate radio frequency signals with the frequency of 2nf in ; S8, the low-phase noise amplifier amplifies the radio frequency signal output by the photoelectric detector to ensure that the gain of the high-frequency multiplication photoelectric oscillation loop is greater than 1, the center frequency of the broadband filter is 2nf in to define the frequency range of the radio frequency signal output by the low-phase noise amplifier and filter harmonic signals of other orders in the radio frequency signal; s9, loading the high frequency multiplication radio frequency signal generated by the system onto the Y-polarization optical carrier signal in the dual-polarization Mach-Zehnder modulator by the through output end of the electric coupler, and outputting the high frequency multiplication radio frequency signal generated by the system outwards by the coupling output end of the electric coupler.
8. The method of generating a high frequency multiplication radio frequency signal by sub-harmonic optical injection locking as claimed in claim 7, wherein the wavelength of the linearly polarized optical carrier signal output by the laser is located at the middle position of two resonance peaks of the fabry perot filter.
9. The method of generating high frequency multiplication radio frequency signals by sub-harmonic optical injection locking according to claim 7, wherein the frequency of the radio frequency signals transmitted by the RF signal source is f in =fsr/2 n, wherein FSR is the free spectral range of the fabry perot filter, and n is the order of the sideband modulated signals output by the polarization beam splitter.

Description

System and method for generating high frequency multiplication radio frequency signal by subharmonic light injection locking Technical Field The invention relates to a system for generating a radio frequency signal, in particular to a system and a method for generating a high-frequency-multiplication radio frequency signal by subharmonic light injection locking. Background With the application and development of microwave technology in the fields of modern communication networks, radar countermeasure, electronic warfare and the like, the frequency and quality of microwave signals are increasingly required. The low frequency of the traditional microwave signal leads to limited information transmission capacity, and the requirements of modern communication on high frequency, wide frequency band and high performance of the microwave signal cannot be met. Therefore, how to generate high-quality high-frequency microwave signals is a urgent problem to be solved. Optoelectronic oscillators (OEOs) are of interest due to their extremely low phase noise and good side-mode rejection ratio. Since the phase noise of the optoelectronic oscillator is independent of the oscillation frequency, it is very suitable for generating a high frequency signal. However, since the optoelectronic oscillator is limited by the quality factor (Q), the higher the frequency of the optoelectronic oscillator, the lower the Q value thereof, and the larger the frequency range of the radio frequency filter thereof. When the frequency range of the filter is insufficient to realize single-mode oscillation, the mode-jump phenomenon is easy to generate, so that the output frequency of the photoelectric oscillator is unstable, and the side mode rejection ratio is reduced, and the requirement of actual work cannot be met. In order to achieve frequency stabilization of the output signal, a frequency multiplication method is proposed, however, for a conventional electronic oscillator such as a quartz oscillator, multistage frequency multiplication is required in order to generate a high-frequency signal. The low-frequency signal is gradually converted into a high-frequency signal by a multi-stage frequency multiplication mode. The frequency doubling conversion process is limited by the frequency tuning range, and the phase noise also gradually worsens along with the frequency doubling, wherein the phase noise worsens to 20lgN degrees, and N is the frequency doubling frequency. Thus, the existing Gao Beipin optoelectronic oscillator has difficulty in generating high-frequency radio-frequency signals with high frequency and low phase noise without a high-frequency signal source. Disclosure of Invention The invention aims to provide a system and a method for generating high-frequency-multiplication radio frequency signals by subharmonic optical injection locking, so as to solve the problem that the existing high-frequency-multiplication photoelectric oscillator is difficult to generate high-frequency and low-phase noise high-frequency radio frequency signals without a high-frequency signal source. The purpose of the invention is realized in the following way: a system for generating a high frequency multiplied radio frequency signal using subharmonic optical injection locking, comprising: The output end of the laser is connected with the optical carrier input end of the dual-polarization Mach-Zehnder modulator and is used for providing a linear polarized optical carrier signal for the system; the output end of the RF signal source is connected with the first 180-degree bridge coupler and is used for transmitting a radio frequency signal with the frequency of f in so as to perform optical injection locking; The first 180-degree bridge coupler is connected with the RF signal source by the input end, and the two output ends of the first 180-degree bridge coupler are respectively connected with one radio frequency input end of a first dual-drive Mach-Zehnder modulator in the dual-polarization Mach-Zehnder modulators; the first 180-degree bridge coupler is used for loading a radio frequency signal sent by an RF signal source onto an optical carrier signal modulated by the first double-drive Mach-Zehnder modulator; The input end of the second 180-degree bridge coupler is connected with the electric coupler, and the two output ends of the second 180-degree bridge coupler are respectively connected with one radio frequency input end of a second dual-drive Mach-Zehnder modulator in the dual-polarization Mach-Zehnder modulators; the second 180-degree bridge coupler is used for loading a high-power radio frequency signal generated by the system onto an optical carrier signal modulated by the second double-drive Mach-Zehnder modulator; The dual-polarization Mach-Zehnder modulator comprises a first branch circuit working in an X polarization state, a second branch circuit working in a Y polarization state and an internal polarization beam combiner connected at the tai