Picosecond pulse generation and its simulation in a nonlinear optical mirror mode-locked laser

A nonlinear mirror composed of a lithium triborate crystal and a dichroic output coupler is used to passively mode lock an Nd:YVO4 laser that is pumped by a diode laser array. A mode-locked output power of 3.2 W, a repetition rate of 178 MHz, a pulse width of 8.4 ps, and a beam quality parameter (M2) of 1.27 are obtained at 1064 nm for a pump power of 10.0 W. The numerical simulation for the steady-state pulse width agrees well with the bandwidth-limited value. A double-pass average gain g(ave) is defined by considering the constancy of the output energy. In the simulation g(ave) is kept as a free parameter, and its value required for the bandwidth-limited pulse is found to be 0.047, whereas its calculated value, based on our definition, is 0.057.