CN-122027022-A - Optical comb frequency locking method and system for realizing phase unbiased estimation from frequency domain

CN122027022ACN 122027022 ACN122027022 ACN 122027022ACN-122027022-A

Abstract

The invention discloses an optical comb frequency locking method and system for realizing phase unbiased estimation from a frequency domain, comprising an optical comb generating and feedback control module, a photoelectric conversion and preprocessing module connected with the optical comb generating and feedback control module in a signal way, a first analog-to-digital conversion module connected with the photoelectric conversion and preprocessing module in a signal way, a first frequency domain phase extraction module connected with the first analog-to-digital conversion module in a signal way, a first phase unbiased estimation module connected with the first frequency domain phase extraction module in a signal way, a frequency deviation extraction module connected with the first phase unbiased estimation module in a signal way, a digital-to-analog conversion and processing module connected with the frequency deviation extraction module in a signal way, and an optical comb generating and feedback control module connected with the digital-to-analog conversion and processing module in a signal way. The invention has the characteristics of small volume, high integration level, strong anti-interference capability and the like, and realizes the high-precision unbiased real-time detection and correction of the repetition frequency of the optical comb.

Inventors

ZHENG QIBIN
Bu Chaohui
ZHOU LIGUO
XU KANG
HUANG YANI
DING LI
Jin Zuanming
ZHU YIMING

Assignees

上海理工大学

Dates

Publication Date: 20260512
Application Date: 20260228

Claims (9)

1. An optical comb frequency locking system for achieving phase unbiased estimation from the frequency domain, comprising: the device comprises an optical comb generating and feedback control module, a photoelectric conversion and preprocessing module, a first analog-to-digital conversion module, a first frequency domain phase extraction module, a first phase unbiased estimation module, a frequency deviation extraction module, a digital-to-analog conversion and processing module and an optical comb generating and feedback control module, wherein the photoelectric conversion and preprocessing module is in signal connection with the optical comb generating and feedback control module; The device comprises a frequency deviation extraction module, a second phase unbiased estimation module, a second frequency domain phase extraction module, a second analog-to-digital conversion module and a high-stability reference source, wherein the second phase unbiased estimation module is in signal connection with the frequency deviation extraction module, the second frequency domain phase extraction module is in signal connection with the second phase unbiased estimation module, the second analog-to-digital conversion module is in signal connection with the second frequency domain phase extraction module, and the high-stability reference source is in signal connection with the second analog-to-digital conversion module.
2. The optical comb frequency locking system for realizing phase unbiased estimation from a frequency domain according to claim 1, wherein an optical signal output by the optical comb generating and feedback control module is subjected to photoelectric conversion and preprocessing to obtain an electrical signal of a single frequency point to be detected, and the electrical signal and the high-stability reference source signal are respectively subjected to synchronous digital sampling by the first analog-to-digital conversion module and the second analog-to-digital conversion module.
3. The optical comb frequency locking system for realizing phase unbiased estimation from a frequency domain as claimed in claim 2, wherein the two sampled digital signals enter a first frequency domain phase extraction module and a second frequency domain phase extraction module and are subjected to complex signal construction in the frequency domain, a phase difference of the two signals is obtained through the first phase unbiased estimation module and the second phase unbiased estimation module, and then the frequency difference is extracted by the frequency deviation extraction module.
4. An optical comb frequency locking method for realizing phase unbiased estimation from a frequency domain is characterized by comprising the following steps: S1, taking a high-stability reference source as a system clock of a digital programmable module; S2, optical signals generated by an optical comb generation and feedback control module are subjected to photoelectric conversion and preprocessing to obtain single-frequency point electric signals to be detected, and the electric signals and high-stability reference source signals are synchronously and digitally sampled by using a first analog-to-digital conversion module and a second analog-to-digital conversion module; S3, inputting signals digitized by the two paths of first analog-to-digital conversion modules and the second analog-to-digital conversion module into a first frequency domain phase extraction module and a second frequency domain phase extraction module to obtain corresponding two paths of complex frequency domain signals; S4, inputting the two paths of complex frequency domain signals into a first phase unbiased estimation module and a second phase unbiased estimation module respectively, and carrying out unbiased estimation on the phases of the two paths of signals in a frequency domain to obtain the phase difference of the two paths of input signals; s5, inputting the phase difference into a frequency deviation extraction module, and calculating to obtain the frequency difference of two paths of input signals; S6, converting the frequency difference in the step S5 into an analog signal form which can be identified by the optical comb generating and feedback control module through the digital-to-analog conversion and processing module, and realizing the real-time locking and correction of the optical comb frequency.
5. The method for locking frequency of optical comb for realizing phase unbiased estimation from frequency domain as claimed in claim 4, wherein in step S2, the output signal of high stability reference source is adjusted to be close to the amplitude level of threshold of second analog-to-digital conversion module, the output frequency of optical comb generating and feedback control module is filtered to single frequency point signal by photoelectric conversion and preprocessing module, and the signal is adjusted to be close to the amplitude level of threshold of first analog-to-digital conversion module, and the two signals are digitally sampled by using first analog-to-digital conversion module and second analog-to-digital conversion module.
6. The method for locking optical comb frequency with phase unbiased estimation from frequency domain according to claim 5, wherein in step S3, the first frequency domain phase extraction module and the second frequency domain phase extraction module are used, and an improved frequency domain analysis method based on data reconstruction and convolution window is used for the phase matching Weighting and aliasing recombination are carried out on the sampling points to construct the phase invariance The point sequence is subjected to Fourier transformation; the first analog-to-digital conversion module and the second analog-to-digital conversion module are used for carrying out the test on the single-frequency point electric signal to be tested And a high stability reference source signal Synchronous digital sampling is carried out, the sampling frequency is set to meet the Nyquist sampling theorem, and the sampling interval is Cut length of single measurement Are respectively recorded as a signal sequence to be measured And a reference signal sequence ; Build a length of Is a convolution window sequence of (2) The convolution window sequence consists of two sequences of length Is a symmetric window function of (2) Performing time domain convolution operation and normalizing the convolution result, which can use various symmetrical window functions to construct convolution window, including but not limited to rectangular window, hanning window, and blackman window, where the rectangular window is taken as an example to construct convolution window, the generated convolution window sequence Is a triangular window.
7. The method for optical comb frequency locking for phase unbiased estimation from frequency domain according to claim 6, wherein the phase unbiased estimation is achieved by convolution Respectively for two paths of collection Windowing the data points, performing data shift, superposition and recombination, and performing data acquisition Data mapping compression of point length to length Is a pre-processing sequence of (2) And The step is equivalent to carrying out the average processing of the full-phase data vector on the original signal through the cyclic recombination of the data, and all the data comprise the central point A kind of electronic device The point Fast Fourier Transform (FFT) is taken into consideration, so that the influence of spectrum leakage caused by signal truncation on the accuracy of phase measurement can be effectively restrained; For pretreatment sequences And Respectively execute Fast Fourier transform of the point to obtain two paths of complex frequency domain signals And 。
8. The optical comb frequency locking method for realizing phase unbiased estimation from frequency domain according to claim 5, wherein said step S4 is embodied as searching complex frequency domain signals respectively And Frequency index corresponding to maximum value of amplitude spectrum And Extracting complex phase angle at the index, and analyzing the characteristic in the main spectral line according to the frequency domain based on the convolution window The phase value at which is equal to the actual phase of the signal at the centre moment, is offset from the frequency Irrelevant, therefore, obtain the unbiased phase of the signal under test And unbiased phase of reference signal Performing differential operation on the two extracted unbiased phase values to calculate the phase difference of the signal to be measured at the current measurement time relative to the reference signal, wherein the phase difference is calculated by the phase difference The phase lead or lag of the optical comb signal relative to the high stability reference source at the center of the current measurement frame is accurately characterized.
9. The method for locking optical comb frequency for realizing phase unbiased estimation from frequency domain according to claim 8, wherein said step S5 is specifically set at the first step Phase difference obtained at time of secondary measurement In the first place The phase difference obtained at the next time is The time interval between the two measurements is Calculating the frequency difference of the two paths of input signals according to the relation between the phase change rate and the frequency The frequency difference Directly reflects the frequency deviation degree and direction of the optical comb signal to be measured relative to the reference source when When the optical comb frequency is higher than the reference frequency When the comb frequency is lower than the reference frequency.

Description

Optical comb frequency locking method and system for realizing phase unbiased estimation from frequency domain Technical Field The invention relates to the technical field of high-precision time measurement and frequency measurement, in particular to an optical comb frequency locking method and system for realizing phase unbiased estimation from a frequency domain. Background With the continuous development of time-frequency technology, various high-stability frequency sources are widely applied to the fields of precision measurement, navigation positioning, information transmission and the like. How to measure the output frequency of a frequency source with high precision, identify tiny fluctuation of the frequency source and correct the frequency source rapidly is always a key problem in the research of a time-frequency system. In a satellite navigation positioning system, once a frequency source fails or the performance of the frequency source is obviously reduced, an abnormal frequency signal is generated, and the normal operation of the whole navigation system is directly influenced. Such anomalies introduce additional positioning errors, increasing uncertainty in the operation of the system and, in severe cases, even causing the satellite to lose navigation capability. Therefore, the realization of high-precision time-frequency measurement and rapid frequency deviation correction is of great importance to ensuring that a navigation system provides accurate and reliable positioning information. In addition, in order to adapt to special application scenes such as satellite load and the like with limited space, the development of a miniaturized and portable frequency measurement and correction system has important practical significance. In optical and optical comb systems, the frequency stability directly determines the measurement accuracy and long-term reliability of the system. However, lasers are susceptible to interference from many factors, such as temperature fluctuations, mechanical vibrations, and environmental noise, during operation, causing random frequency drift or sudden jumps. Such frequency anomalies can severely limit the effective bandwidth and measurement sensitivity of the optical comb system, thereby affecting the application performance in the fields of precision spectroscopy, optical metrology, and the like. Therefore, high-precision frequency detection means are urgently needed to capture the frequency fluctuation and jump accurately in real time and correct the frequency fluctuation and jump rapidly, so that the influence of frequency instability on the overall performance of the system is reduced, and the measurement precision and sensitivity are improved. The traditional frequency locking scheme usually depends on an optical cavity or a resonant cavity structure to realize frequency stabilization, but the problems of huge device volume, complex debugging process, easy environmental interference and the like of the methods generally exist, so that the popularization and the application of the methods in portable equipment and practical engineering environments are limited. Therefore, there is a need to develop a frequency locking technology capable of accurately detecting the frequency variation of the optical comb in real time and realizing fast feedback correction, so as to make up for the defects of the existing methods and promote the development of the related technology to the integration and practical directions. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide an optical comb frequency locking method and system for realizing phase unbiased estimation from a frequency domain, a digital programmable logic circuit is utilized to construct a full digital frequency locking loop, and phase measurement errors caused by spectrum leakage are effectively overcome through a data recombination and frequency domain phase unbiased estimation technology based on a convolution window. The reference source with high stability is used as a system unified clock, a complex frequency domain signal is constructed in a digital programmable logic circuit by synchronous digital sampling of the reference signal and the optical comb signal, and phase unbiased estimation is realized in a frequency domain, so that frequency difference is extracted with high precision, and quick feedback correction is realized. To achieve the above objects and other advantages and in accordance with the purpose of the invention, there is provided an alcohol-gas mixture control method for improving performance of a methanol engine, comprising: the device comprises an optical comb generating and feedback control module, a photoelectric conversion and preprocessing module, a first analog-to-digital conversion module, a first frequency domain phase extraction module, a first phase unbiased estimation module, a frequency deviation extraction module, a digital-to-analo