Yang Kangwen

Nonlinear polarization rotation-induced pulse shaping in a stretched-pulse ytterbium-doped fiber laser

We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of ~ 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.

Phase noise suppression and feedback control of carrier-envelope phase in an Yb-doped fiber frequency comb

In this letter, we study the carrier envelope phase noise induced by the effects of LD-pump jitter, temperature change and mechanical vibration on an Yb-doped fiber frequency comb. Based on a home-made Yb-doped fiber oscillator with 60 MHz repetition rate, after two- stage amplifiers and a self-referenced f-2f measurement system, a beat signal with a signal to noise ratio of 25 dB is obtained. Further the frequency of carrier envelope phase signal is locked through phase-lock-loop electronics, a measured residual frequency jitter of 283 mHz is achieved in 0.5 h accumulation time.

Pump-induced carrier envelope offset frequency dynamics and stabilization of an Yb-doped fiber frequency comb

In this paper, we demonstrate a carrier envelope phase-stabilized Yb-doped fiber frequency comb seeding by a nonlinear-polarization-evolution (NPE) mode-locked laser at a repetition rate of 60 MHz with a pulse duration of 191 fs. The pump-induced carrier envelope offset frequency (f0) nonlinear tuning is discussed and further explained by the spectrum shift of the laser pulse. Through the environmental noise suppression, the drift of the free-running f0 is reduced down to less than 3 MHz within an hour. By feedback control on the pump power with a self-made phase-lock loop (PLL) electronics the carrier envelope offset frequency is well phase-locked with a frequency jitter of 85 mHz within an hour.