Study On Ultra-low Timing Jitter Femtosecond Fiber Laser Oscillators And Their Applications

Femtosecond fiber lasers exhibit inherently low timing jitter.They are compact,low in price,insensitive to environmental perturbations,easy to operate and maintain,and thus an ideal choice for pulsed laser source in advanced applications.Along with the development of the noise theory in femtosecond lasers,properties and corresponding impacts of timing jitter have been better understood in relevant fields.The balanced optical cross-correlation method has made it possible to characterize and optimize the timing jitter in femtosecond lasers with unprecedented resolution.This thesis is aimed at quantum-limit timing jitter optimization in femtosecond Ytterbium-doped fiber lasers,and the impact of intra-cavity dynamics is systematically studied with both numerical simulation and experimental setups.Furthermore,time-of-flight metrology and low-jitter timing signal extraction experiments based on femtosecond fiber lasers are carried out.This thesis is basically structured as follows:1.Numerical model of timing jitter characterization in femtosecond Yb-fiber lasers is developed based on the nonlinear Schr?dinger equation,the Ginzburg-Landau equation,and the semi-classical amplified spontaneous emission noise model in the quasi-three-level gaining medium.The timing jitter level and corresponding leading influence factors in conditions with various intra-cavity net dispersion and filter parameters are simulated and then analyzed according to the intra-cavity dynamics of each condition.2.A timing jitter characterization system is built upon the balanced optical cross-correlation method.The reference laser is a femtosecond Yb-fiber laser operating in the stretched-pulse regime and the laser under test has the same structure with varying net dispersion and filtering conditions.By synchronizing the repetition rate of the laser under test to the reference,the timing jitter can be characterized with attosecond resolution.Upon insertion of a 7.7-nm narrow band-pass filter,the timing jitter component indirectly coupled from the amplified spontaneous emission is sufficiently suppressed.When integrated from 10 kHz to 10 MHz,the jitter level with different net dispersion is stabilized between 0.6 fs and 1.1 fs.3.The jitter-stabilized femtosecond Yb-fiber laser is utilized in a time-of-flight metrology system with Michelson interferometer structure.Armed with the attosecond resolution of the balanced optical cross-correlation method,the timing offset between target-reflected pulses and reference pulses is precisely characterized and tightly locked to zero.The distance under test can then be calculated with the repetition rate information of the femtosecond laser.A 52 m free space distance is measured in laboratory environment,and the resolution is 12 nm in 1 s averaging time.When the distance under test is zero,the resolution limit of the metrology system reaches 4 nm in 1 s averaging time.4.A timing reception system is built upon a femtosecond fiber laser with ultra-low timing jitter and a balanced optical cross-correlation system with attosecond-level timing resolution.Then,a demonstrative low-jitter timing signal extraction experiment is carried out,together with the reference laser as the master clock signal.Besides quantum-limit timing jitter suppression,the residual timing error between the master clock and the reception system is further suppressed via an intra-cavity electro-optic modulator.The locking bandwidth is increased to 400 kHz,and the timing resolution of the entire reception system is 13 as,when integrated from 1 Hz to 10 MHz.The lowest residual timing error between the master clock and the reception system is measured to be 109 as,which is less than one-thirtieth of the carrier cycle in the 1 micron range.