Single-frequency laser pumped optical parametric oscillator at 226 nm

We demonstrate a narrow linewidth optical parametric oscillator (OPO), with a 452 nm signal radiation output, pumped by a 355 nm single frequency Nd:YAG laser. The pump laser can operate with a precisely controllable laser pulse firing time and so can the OPO output. The OPO is composed of two beta barium borate crystals and arranged in a linear cavity configuration. The cavity is not actively stabilized. The maximum output pulse energy achieved for the 452 nm signal is 11 mJ with a 45 mJ pump energy. The spectrum and spatial shape are measured to be in accordance with the pulse characteristics of a narrow linewidth laser. It is shown that the signal pulse is extremely dependent on the pump pulse. Then the signal pulse is frequency doubled to generate about 1.5 mJ in energy of ultraviolet radiation at 226 nm.