High-efficiency continuously tunable single-frequency doubly resonant optical parametric oscillator

We report a high-efficiency continuously tunable single-frequency doubly resonant optical parametric oscillator (OPO) based on periodically poled KTiOPO4. Pumped by a frequency-doubled Nd:YLF laser at 526.5 nm, the OPO has a low threshold of 30 mW and can deliver up to 156 mW single-frequency output at 0.8 μm and 89 mW single-frequency output at 1.5 μm with 390 mW of pump power. Coarse and continuous frequency tuning are also demonstrated experimentally.