	US 12,424,814 B2
	Method and device for automatically locking repetition frequency and carrier-envelop offset frequency of optical frequency comb
Zhitao Zhang, Beijing (CN); Tieli Zhang, Beijing (CN); Yinxiao Miao, Beijing (CN); Xiaoqiang Gao, Beijing (CN); Beibei Wang, Beijing (CN); Hao Liu, Beijing (CN); Yongyao Xu, Beijing (CN); Weiwei Wu, Beijing (CN); and Yan Song, Beijing (CN)
Assigned to BEIJING AEROSPACE INSTITUTE FOR METROLOGY AND MEASUREMENT TECHNOLOGY, Beijing (CN)
Filed by BEIJING AEROSPACE INSTITUTE FOR METROLOGY AND MEASUREMENT TECHNOLOGY, Beijing (CN)
Filed on May 15, 2025, as Appl. No. 19/209,685.
Claims priority of application No. 202410882449.9 (CN), filed on Jul. 3, 2024.
Prior Publication US 2025/0273922 A1, Aug. 28, 2025
Int. Cl. H01S 3/13 (2006.01); G02F 1/35 (2006.01); H01S 3/00 (2006.01); H01S 3/04 (2006.01); H01S 3/10 (2006.01); G04F 5/14 (2006.01)

CPC H01S 3/1305 (2013.01) [G02F 1/353 (2013.01); H01S 3/0078 (2013.01); H01S 3/0405 (2013.01); H01S 3/1001 (2019.08); G02F 2203/56 (2013.01); G04F 5/14 (2013.01)]

10 Claims

1. A method for automatically locking repetition frequency and carrier-envelope offset frequency of optical frequency comb, comprising:

converting a repetition frequency optical signal of the optical frequency comb under a microwave frequency into a microwave repetition frequency signal f_r, and converting a carrier-envelope offset frequency optical signal of the optical frequency comb under the microwave frequency into a microwave carrier-envelope offset frequency signal f₀; wherein a repetition frequency refers to a reciprocal of a time interval between two adjacent pulses in an optical pulse train; the repetition frequency represents a pulse period in a time domain; the repetition frequency represents a spacing between adjacent comb teeth in the frequency domain; a carrier-envelope offset frequency represents an overall frequency offset of the optical pulse train;

performing automatic locking of the microwave repetition frequency signal f_rthrough steps of:

filtering the microwave repetition frequency signal f_rto obtain a filtered signal;

mixing the filtered signal with a first reference signal followed by phase discrimination to obtain a first error signal; wherein the first reference signal is generated by a frequency synthesizer;

splitting the first error signal into a first sub-signal and a second sub-signal;

converting the first sub-signal into a first voltage signal;

adjusting a first output frequency of the frequency synthesizer based on a direction of the first error signal and the first voltage signal until a frequency of the first error signal is below 10 Hz;

collecting, by an analog-to-digital converter, the second sub-signal;

processing, by a first adaptive Proportion-Integration-Differentiation (PID) controller, the second sub-signal to obtain a first processed signal;

converting, by a first digital-to-analog converter, the first processed signal into a first control signal; and

amplifying, by a piezoelectric ceramic driver, the first control signal to control a piezoelectric ceramic, so as to achieve automatic locking of the microwave repetition frequency signal f_r; and

performing automatic locking of the microwave offset frequency signal f₀through steps of:

subjecting the microwave offset frequency signal f₀to filtering, frequency division, and phase discrimination with a second reference signal to obtain a second error signal;

splitting the second error signal into a third sub-signal and a fourth sub-signal;

subjecting the third sub-signal to down-conversion to obtain a second voltage signal;

adjusting a second output frequency of the frequency synthesizer based on a direction of the second error signal and the second voltage signal until a frequency of the second error signal is below 100 Hz;

collecting, by the analog-to-digital converter, the fourth sub-signal;

processing, by a second adaptive PID controller, the fourth sub-signal to obtain a second processed signal;

converting, by a second digital-to-analog converter, the second processed signal into a second control signal;

converting the second control signal into a control current; and

applying the control current to a pump laser to control an output light intensity of the pump laser, so as to achieve automatic locking of the microwave offset frequency signal f₀.