Synchronously pumped femtosecond optical parametric oscillator with integrated sum frequency generation

A synchronously pumped femtosecond optical parametric oscillator (OPO) with intracavity sum frequency generation in a single, periodically poled MgO-doped LiNbO3 (MgO:PPLN) is reported. The used MgO:PPLN crystal contains in series two sections with different poling periods. The first section which generates the 2.5μm OPO idler wave is followed by a second section which generates the sum frequency of the pump and the idler radiation and thus provides at 589nm yellow 140fs long pulses with an average power of up to 190mW. This corresponds to an optical overall conversion efficiency of 15%.