Effects of nonlinear phase in cascaded mode-locked Nd:YVO 4 laser.

A diode-pumped mode-locked Nd:YVO ₄ laser via positive cascaded second-order Kerr lens using periodically poled MgO:LN at 1064 nm was reported. Mode-locking performances including output power, bandwidth, pulse duration, and time-bandwidth product were studied under different phase-mismatched conditions. The induced nonlinear phase combined with soft aperture effect yield a stable mode-locked operation in a wide phase-mismatched range (-8π < ∆kL < -π). Additionally, the mode-locking bandwidth was broadened by self-phase modulation and the time-bandwidth product was increased to be more than twice the ideal product for a sech ² pulse shape. Under 11 W diode pump power, the measured average power, pulse repetition rate and pulse duration are 1.3 W, 186 MHz and 2.8 ps, respectively.