One-step generation of a visible to deep-ultraviolet tunable laser from a near-infrared ultrafast light source

For the first time, to our knowledge, the cascading effects of self-phase modulation and second-harmonic generation (SPM-SHG) in a nonlinear optical medium were used to conveniently convert a near-infrared ultrafast laser with a fixed center wavelength into a visible to deep-ultraviolet (DUV) laser with a continuously tunable wavelength.When a -BaB 2 O 4 (BBO) crystal was used as the nonlinear optical medium, and a Ti:sapphire laser (800 nm, 38 fs) was used as the fundamental light source, the output wavelength had a tunable range of 225-460 nm, and the highest optical conversion efficiency reached 18.1% at 361 nm.For a 1030 nm fundamental light source, the shortest output wavelength was also 225 nm by one-step frequency conversion of the BBO crystal.By further frequency conversions, the tunable wavelength can extend to the vacuum ultraviolet (VUV) waveband, as short as 193 nm.These results demonstrated that SPM-SHG could be used as an extremely simple and effective frequency conversion method to obtain a wideband tunable ultraviolet laser.