Low-pump-threshold continuous-wave singly resonant optical parametric oscillator

We describe a compact all-solid-state continuous-wave singly resonant optical parametric oscillator (SRO) with a minimal pump-power requirement. The SRO is based on periodically poled ${\mathrm{LiNbO}}_3$ as the nonlinear material and is pumped by a 1-W diode-pumped $\mathrm{Nd}:{\mathrm{YVO}}_4$ minilaser at $1.064 \mathit{\mu }\mathrm{m}$. By exploiting the intracavity pumping technique in a 50-mm crystal, we have achieved SRO operation threshold at a diode pump power of only 310 mW. At 1 W of input diode power, the SRO delivers 70 mW of output power in the nonresonant idler at $3.66 \mathit{\mu }\mathrm{m}$, at a photon conversion efficiency of 55%. Multiparameter tuning of the SRO yields a signal wavelength range from 1.45 to $1.60 \mathit{\mu }\mathrm{m}$ and an idler wavelength range from 3.16 to $4.02 \mathit{\mu }\mathrm{m}$ in the mid infrared. The device is characterized by robust turnkey operation and long-term amplitude-stable performance.