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Femtosecond optical parametric oscillator based on periodically poled KTiOPO4

We describe a synchronously-pumped optical parametric oscillator (OPO) based on periodically poled KTiOPO4(PPKTP). The OPO was pumped by a self-mode-locked Ti:sapphire laser. Its signal wave covers from 1070 nm to 1375 nm, and could be tuned freely by cavity-length tuning, the corresponding idler wave covering from 1.9 μm to 3.2 μm in the mid-infrared region. Red, green and blue visible light were also generated by intra-cavity sum frequency or frequency doubling. The threshold was measured to be about 250 mW at 810 nm pump. A thin glass substrate was inserted to the cavity for output coupling, and the maximal output power was measured to be 26 mW. We adopted ring cavity and linear cavity experimentally. After optimization, the output characteristics of the ring cavity and linear cavity were investigated respectively. The approach to improve the output efficiency was also discussed.