Study Of Laser Frequency Stabilization Based On Erbium-doped Fiber Femtosecond Optical Frequency Comb

Optical comb is a bridge to connect optical and microwave frequency band,which has been applied in various fields,such as optical frequency measurement,absolute distance measurement and astronomical observation etc..At present,optical comb is currently under the gradual transition from Ti-sapphire optical frequency comb to fiber optical comb with more compact size,stable operation,and lower cost.Meanwhile,the laser frequency stabilization can be achieved by using the characteristics of optical comb and optical phase-locked loop.Compared with the traditional frequency stabilization methods,this method is strictly phase-locked to the microwave frequency standard,which enables its reappearance value to be immune to the influence of environment,such as external temperature and magnetic field etc.,and to have better stability and reproducibility as well as to obtain the absolute value of the laser frequency directly.Therefore,this paper mainly focuses on erbium-doped fiber comb and laser frequency stabilization.The main work is as follows:?1?A set of erbium-doped fiber comb is established by our laboratory,and the signal-to-noise ratio?SNR?of the carrier-envelop-offset frequency(f_ceo)is obtained about 35 dB.In addition,a set of equipment for locking repetion frequency(f_rep)and f_ceoeo are designed and built by myself,and the f_repep and f_ceoeo are locked for 48 hours continuously.f_repep and f_ceoeo is counted when they are locked and the the sampling time is at 1s intervals.The standard deviations of f_repep and f_ceois 0.327 mHz and 0.568 mHz,respectively.?2?After the optical comb being locked,the frequency of 1.5?m semiconductor laser is locked to the optical comb by the construction of the optical phase-locked loop with an absolute frequency stabilized at the standard value of 1.5?m?194369569384000 Hz?recommended by the International Committee for Weights and Measures?CIPM?,and it can be locked stably for 2 hours.To count under the conditions that the sampling time is at 1s intervals,the standard deviations of beat frequency(f_beat)after being locked is 0.348 mHz.Meanwhile,laser frequency stabilization will be achieved again after tuning the laser.?3?The partial work for stabilizing the laser of 852 nm is completed:a light path is built to shift frequency of 852 nm external cavity semiconductor laser.And the SNR of f_beateat is 30 dB,which is achieved by the laser after shifting frequency and FC1500 optical comb of Menlosystems GmbH.?4?The circuit of tracking oscillator is designed to track the beat frequency of1.5?m semiconductor laser and opical comb.