Generation of vacuum-ultraviolet light below 160 nm in a KBBF crystal by the fifth harmonic of a single-mode Ti:sapphire laser

Abstract

We have generated a vacuum-ultraviolet light below 160 nm by sum-frequency mixing in an optically contacted, prism-coupled KBe2BO3F2 crystal. The vacuum-ultraviolet light was generated as the fifth harmonic of a tunable, single-mode, 1-kHz Ti:sapphire laser system. The wavelength of 156 nm, to our knowledge, is the shortest ever obtained by use of nonlinear crystals in a phase-matched process. In addition, we demonstrated a 157.6-nm light source as an inspection tool for F2 laser lithography with an average power of 0.8 μW.