Optical frequency comb carrier envelope offset frequency locking device and method

Abstract

The invention discloses an optical frequency comb carrier envelope offset frequency locking device and method, and belongs to the technical field of optical frequency comb laser. The device mainly comprises an optical frequency comb, a band-pass filter, a radio frequency amplifier, a low-pass filter and a proportional integral differentiating circuit (PID) which are sequentially connected through radio frequency transmission lines. The optical frequency comb inputs a carrier envelope offset frequency signal to the band-pass filter, and an output signal of the proportional integral differentiating circuit is fed back to a seed source driving current of the optical frequency comb to form a closed loop. The carrier envelope offset frequency f0 signal and the fr-f0 signal have the same source, and the beat signal noise formed by superposition of the two signals is suppressed, so that the locking tracking precision can be improved; and the locked carrier envelope offset frequency is strictly equal to half of the repetition frequency, and the optical comb can be stable after the repetition frequency is locked. The device has the advantages of high locking and tracking precision, simple structure, convenience in operation, no need of a signal source and a phase discrimination circuit, low cost and the like.

Description

technical field [0001] The invention relates to an optical frequency comb carrier envelope offset frequency locking device and method, belonging to the technical field of optical frequency comb lasers. Background technique [0002] The ultrafast femtosecond laser based on mode-locked pulses is a series of periodic output pulses in the time domain, and a series of equally spaced spectral lines in the frequency domain. The frequency interval between the spectral lines is equal to the pulse repetition frequency (f r ), the frequency of the nominally most initial spectral line is called the carrier envelope offset frequency (f 0 ). The femtosecond laser whose repetition rate and carrier envelope offset frequency are locked is called an optical frequency comb, or optical comb for short. It has ultra-high frequency stability and is the physical basis for precision measurement using femtosecond laser. Therefore, frequency locking between repetition rate and carrier envelope offse...

AI Technical Summary

Problems solved by technology

Since the carrier envelope offset frequency signal carries relatively large noise, the requirements for the phase detection circuit are relatively high, and it is also prone to problems such as poor locking tracking and short locking time.

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