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Optical frequency combs are increasingly being adopted in various measurement applications. However, the sensitivity of free-running optical frequency combs and the large size and complex connections required for locking equipment pose significant obstacles to their on-site application. To address these challenges, we present an integrated optical frequency comb repetition rate locking control system that greatly reduces the volume of the locking system.In this system, we firstly control the temperature of the resonator cavity to achieve a wide range of control over the effective length of the cavity. A temperature control box for the resonator cavity is designed, incorporating semiconductor cooling chips to regulate the temperature. Secondly, we employ piezoelectric ceramics to achieve small-scale stretching control of the resonator cavity length. These control methods work in synergy to achieve high-quality repetition rate locking. The use of a loop filter in the system establishes the dynamic performance of the repetition rate locking loop and effectively suppresses the high-frequency components of the phase discriminator output. Through testing of the research system, the temperature control system demonstrates a temperature control range of 20-40°C, with a temperature control accuracy of ±0.01°C. With the assistance of the temperature control system, the repetition rate locking system achieves a repetition rate locking duration of over 10 hours, with a fluctuation range of less than 5 mHz, an Allan deviation of 217 μHz@gate 1s, and a relative frequency stability of 3.89E-12.This system successfully achieves high-frequency stability and long-term locking of the optical frequency comb's repetition rate.
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