Passively mode locked operation of diode pumped Nd:YVO4 laser using either second harmonic nonlinear mirror or semiconductor saturable absorber

Results of experimental investigation of diode pumped Nd:YVO4 laser passively mode locked using either second harmonic nonlinear mirror or semiconductor saturable absorber are reported. As an active element the 5 mm long Nd:YVO4 crystal end pumped by 20 W fiber coupled laser diode was used. The linear folded resonator has on the other end either saturable absorber with single 15 nm thick In0.25Ga0.75As quantum well layer integrated on the top of Bragg mirror (SESAM) either nonlinear mirror (NLM) consisting of a dichroic dielectric mirror and 10 mm long type I LBO crystal critically phase matched for second harmonic generation. Using the nonlinear mirror the threshold for mode locked operation was 10 W of pump power and we obtained 4.5 W of output power with single pulse duration of 6.2 ps for pump power of 15 W. Using the SESAM the pulse duration of 13-16 ps was achieved for pump power from 3W to 18 W for low output coupling.