Bismuth functionalized GaAs as saturable absorber for passive Q-switching at 1.34 μm

First principles simulations showed bismuth doped GaAs could modify the electronic band structure. Hereby, Bi:GaAs exhibited excellent nonlinear absorption properties at 1.3 mu m with a modulation depth of 6.2%, larger than that of pure GaAs. Subsequently, the passively Q-switched Nd:YVO4 lasers were demonstrated at 1.34 mu m with Bi:GaAs and GaAs the saturable absorbers. Stable pulses with the shortest duration of 64 ns at a repetition rate of 138 kHz were generated with Bi:GaAs saturable absorber. In the meantime, we also observed Bi ion doping accelerates the free-carrier recovery, indicating Bi:GaAs excellent candidant for 1.3 mu m pulse generation.