Picosecond 175 ∼ 210 nm tunable deep-ultraviolet laser

A picosecond tunable deep-ultraviolet laser by two stages of second harmonic generation (SHG) was developed with a fundamental tunable Ti:sapphire laser from 700 to 840 nm. In the first SHG stage, two β-BaB₂O₄ crystals was adopted to compensate the walking of the beam direction due to frequency-tuning, which improved beam quality and increased output power. The tunable wavelength of first SHG stage was 350 ~ 420 nm, and the maximum output power was 1.1 W at 386 nm. In the second SHG stage with a KBe₂BO₃F₂ as nonlinear optical crystal, the tunable range was 175 ~ 210 nm, and the highest power was 3.72 mW at 193 nm.