CN-122027019-A - High-repetition-frequency optical frequency comb mode locking detection method and system

CN122027019ACN 122027019 ACN122027019 ACN 122027019ACN-122027019-A

Abstract

The invention provides a high repetition frequency optical frequency comb mode locking detection method and system, which are characterized in that an optical frequency comb repetition frequency theoretical value is calculated according to the cavity length of an optical frequency comb optical system, pumping light is injected into the optical frequency comb optical system, an output light converts an optical signal into an electric signal through a photoelectric detector, the electric signal filters out and amplifies a fundamental frequency signal of the optical frequency comb repetition frequency through a band-pass amplifier, then the fundamental frequency signal is reduced to a KHz level through a frequency division amplification signal processing unit and enters an analog-to-digital converter, the current frequency division level and the frequency division ratio of the frequency division amplification signal processing unit are determined by a microcontroller according to the optical frequency comb theory repetition frequency theoretical value, the microcontroller processes a signal acquired by the analog-to-digital converter to obtain frequency spectrum information, the optical frequency comb is unlocked when the fluctuation of the intensity corresponding to the frequency spectrum information in a certain time period is larger than a set threshold value, and the optical frequency comb is locked when the fluctuation of the intensity of the frequency spectrum information in a certain time period is not larger than the set threshold value. The invention can accurately detect the mode locking state of the high repetition frequency optical frequency comb.

Inventors

ZHANG ZHITAO
LIU HAO
MIAO YINXIAO
ZHANG TIELI
GAO XIAOQIANG
SONG YAN
WU WEIWEI
WANG BEIBEI
XU YONGYAO
ZHANG YONGCHAO

Assignees

北京航天计量测试技术研究所

Dates

Publication Date: 20260512
Application Date: 20251125

Claims (10)

1. A high repetition frequency optical frequency comb mode locking detection method is characterized in that an optical frequency comb repetition frequency theoretical value is calculated according to the cavity length of an optical frequency comb optical system; Pumping light is injected into an optical system of the optical frequency comb, an output light converts an optical signal into an electric signal through a photoelectric detector, the electric signal filters out and amplifies a fundamental frequency signal of the repetition frequency of the optical frequency comb through a band-pass amplifier, then the frequency is reduced to the KHz level through a frequency division amplification signal processing unit, and then the electric signal enters an analog-to-digital converter; The current frequency division level number and frequency division ratio of the frequency division amplification signal processing unit are determined by a microcontroller according to the optical frequency comb theory repetition frequency theoretical value; the microcontroller processes the signals collected by the analog-to-digital converter to obtain frequency spectrum information, the optical frequency comb is not in a mode when the fluctuation of the intensity corresponding to the frequency point in the frequency spectrum information in a certain time period is larger than a set threshold value, and the optical frequency comb is in a mode locking mode when the fluctuation is not larger than the set threshold value.
2. The method of high repetition rate optical frequency comb mode locking detection of claim 1 wherein the frequency division amplified signal processing unit comprises more than two frequency dividers and amplifiers, the number of frequency dividers and amplifiers being identical, one frequency divider and one amplifier being a unit.
3. The method for detecting the optical frequency comb mode locking of the high repetition frequency according to claim 1, wherein the microcontroller controls the frequency division amplifying signal processing unit through the frequency division amplifying management unit.
4. The method for detecting the mode locking of the high repetition frequency optical frequency comb according to claim 3, wherein the frequency division and amplification management unit is a radio frequency switch, and the number of stages of the currently selected frequency divider and amplifier is managed by controlling the on-off of the radio frequency switch.
5. The method for detecting the mode locking of the high repetition frequency optical frequency comb of any one of claims 1 to 4, wherein the detection result of the mode locking state of the system is output through a logic level, 0 indicates that the mode is unlocked, and 1 indicates that the mode is locked.
6. The method for detecting the mode locking of the high repetition frequency optical frequency comb of claim 1, wherein after the mode locking is detected for the first time, the microcontroller continues to process the signals collected by the analog-to-digital converter, and continuously judges whether the optical frequency comb is actually mode locked.
7. The high repetition frequency optical frequency comb mode locking detection method of claim 5, wherein pump light is injected into the optical frequency comb optical system through a pump source circuit; When the pump source circuit increases to the maximum output power, the fluctuation of the intensity extracted by the microcontroller in a certain period of time is still larger than the set threshold value, and the optical frequency comb is not in a mode.
8. The method of claim 7, wherein when the optical frequency comb mode is locked, the microcontroller determines the change of the frequency spectrum information, and inputs the result to the pump source circuit through the logic level, and the pump source circuit turns off the pump light.
9. The method for detecting the mode locking of the high-repetition-frequency optical frequency comb according to claim 5, wherein the detection result of the mode locking state of the system is indicated by an indicator lamp, the mode locking display is carried out on a first designated color, the mode locking display is carried out on a second designated color, the optical frequency comb optical system is abnormal, and the indicator lamp alternately flashes on the first designated color and the second designated color.
10. The high repetition frequency optical frequency comb mode locking detection system is characterized by comprising an optical frequency comb optical system, a photoelectric detector, a band-pass amplifier, a frequency division amplification signal processing unit, an analog-to-digital converter and a microcontroller; The optical frequency comb optical system is used for receiving the pumping light to complete mode locking, and the photoelectric detector is used for converting an optical signal of light output by the optical frequency comb optical system into an electric signal; The frequency division amplification signal processing unit is used for reducing the frequency of the amplified optical frequency comb repetition frequency fundamental frequency signal to KHz magnitude; the analog-to-digital converter is used for collecting the optical frequency comb repetition frequency fundamental frequency signals after frequency reduction and sending the signals to the microprocessor; The microcontroller is used for determining the current frequency division level and frequency division ratio of the frequency division amplification signal processing unit according to the optical frequency comb theory repetition frequency theoretical value, processing signals collected by the analog-to-digital converter to obtain frequency spectrum information, wherein the optical frequency comb is unlocked when the fluctuation of the intensity corresponding to the frequency point in the frequency spectrum information in a certain time period is larger than a set threshold value, and the optical frequency comb is locked when the fluctuation is not larger than the set threshold value.

Description

High-repetition-frequency optical frequency comb mode locking detection method and system Technical Field The invention relates to the technical field of ultrafast optics, in particular to a high-repetition-frequency optical frequency comb mode locking detection method and system. Background The optical frequency comb is used as a core bridge for connecting an optical frequency scale and a microwave frequency scale, has the obvious advantages of simple structure and low cost, can realize high-precision measurement of absolute optical frequency by the comb spectrum characteristic, provides a revolutionary tool for time frequency transmission, absolute distance and angle measurement, and is a key technical support for precision measurement and engineering application in the fields of manned aerospace, deep space exploration, satellite time service, modern manufacturing industry and the like by the multichannel parallel measurement and phase synchronization technology, so that the parameter measurement precision and the system integration degree under a complex scene are effectively improved. At present, an optical frequency comb mainly comprises an optical fiber optical frequency comb, an electro-optical comb and a microcavity optical comb, wherein the repetition frequency of the electro-optical comb and the microcavity optical comb can generally reach GHz level, the optical frequency comb belongs to high repetition frequency, engineering application is really realized, stable mode locking of an oscillator is a primary premise, the repetition frequency of the optical frequency comb and carrier envelope phase frequency are strictly locked in a mode locking state so as to ensure absolute stability of comb tooth frequency, however, the mode locking process is extremely easy to be interfered by external environment conditions, deformation of mechanical structures, optical fibers, a mirror frame and other optical elements in the optical frequency comb system is caused by environmental temperature change or mechanical vibration, so that the coupling efficiency of an optical system is reduced, the mode locking threshold of pumping current is pushed up, meanwhile, the mode locking threshold of the pumping current is different in different environment conditions, the mode locking stability cannot be ensured by a traditional control mode for fixing the pumping threshold, the mode locking quality is also directly influenced, and even the mode locking fails in serious conditions. The current judgment on the optical frequency comb mode locking state mainly comprises an optical means and an electrical means, wherein the optical means directly measures the spectral change in the mode locking process through a spectrometer, the spectrum is widened and flattened to be used as the representation of the mode locking completion, but the method relies on offline measurement equipment, real-time online monitoring cannot be realized, the electrical means mainly reflects the mode locking state through measuring optical frequency comb repetition frequency related parameters, and is realized through equipment such as a common frequency counter, a spectrometer and the like, although the optical frequency comb with hundreds of MHz and even GHz level of repetition frequency has certain instantaneity, the existing measurement equipment has limitation on high-frequency signal processing precision, and although the related report of judging by adopting a microcontroller to control a peak detector exists, the peak detection module has inherent bandwidth limitation, the mode locking state of the optical frequency comb with high repetition frequency cannot be accurately detected, and misjudgment is easy to be caused. More importantly, the current optical frequency comb technology is rapidly developed towards the directions of high repetition frequency, wide spectral range, miniaturization and integration, the miniaturization and real-time formation of a high repetition frequency optical frequency comb mode locking judging system are necessary development directions, the existing mode locking judging modes all have respective technical bottlenecks, engineering application requirements cannot be met independently, meanwhile, an optical frequency comb can only perform nonlinear transformation such as amplification, spectrum expansion and frequency multiplication after mode locking is completed, otherwise, irreversible damage can be caused to the system, an existing measuring instrument can only feed back a mode locking judging result to an operator, real-time linkage cannot be formed between the optical frequency comb and an optical frequency comb pumping circuit, when the optical frequency comb is out of lock due to external environment interference, the pumping circuit cannot be triggered to be closed or parameter adjustment at first time, the whole optical frequency comb system is extremely easy to damage, and popularization and application of