All-Solid-State DUV Light Source by Quadrupling of an Acousto-Optically Q-Switched Nd:YVO4 Laser

All-solid-state 228.5 nm Deep Ultraviolet (DUV) laser has been studied with two-step second harmonious generation (SHG) of Nd:YVO4 914 nm fundamental laser, by optimizing its resonator design and SHG configurations. Adopting three-mirror folded V cavity and acousto-optical Q-switching, high peak power 457 nm laser output has been achieved by intracavity frequency-doubling of LD pumped Nd:YVO4 914 nm fundamental laser. At pump power of 41 W, the average output power for 457 nm laser has reached 600 mW at repetition frequency 10 kHz, 50 ns pulse width. With Type-I phase matching BBO crystal, external frequency doubling of 457 nm blue output was realized and optimized. Under LD pump power of 41 W, DUV laser at 228.5 nm with average output power of 35 mW has been achieved, at repetition frequency 10 kHz and pulse width of 46 ns. Under these conditions, the frequency doubling conversion efficiency is 5.8%, and the DUV laser output power instability is less than 2% in 2-hour test.