Hybrid femtosecond laser system based on a Yb:KGW regenerative amplifier for N_P polarization

We report a hybrid femtosecond laser system based on a femtosecond Yb-doped fiber laser and a Yb-doped potassium gadolinium tungstate(Yb:KGW) regenerative amplifier. To match the central wavelength of the seed source, a Yb:KGW crystal is used in the regenerative amplifier for N_p polarization. We study and optimize the dynamics of nonlinear amplification to alleviate the gain narrowing effect. With optimization, the system can output 270 fs pulses with 21 μJ pulse energy at a 60 kHz repetition rate.     

Strain compensated robust semiconductor saturable absorber mirror for fiber lasers

We demonstrate a strain compensated long lifetime semiconductor saturable absorber mirror(SESAM) with a high modulation depth for fiber lasers. The SESAM was measured to have a damage threshold of 9.5 m J/cm~2, a modulation depth of 11.5%, a saturation fluence of 39.3 μJ/cm~2, and an inversed saturable absorption coefficient of 630 m J/cm~2. The SESAM has been applied to a linear cavity mode-locked Yb-doped fiber laser, which has been working for more than a year without damage of the SESAM.