Efficient tunable ultraviolet generation in periodically poled lithium niobate

Summary form only given. Tunable pulsed blue and ultraviolet solid state lasers are useful sources for laser isotope separation (LIS), underwater transmission and spectroscopy of atoms, molecules and semiconductors. For spectroscopic and LIS applications a narrow bandwidth is often required. Frequency doubled gain-switched Ti:sapphire lasers are convenient sources in this spectral region. However, the suitable critically-phase-matched (CPM) nonlinear crystals-BBO, LBO, KDP and LIO/sub 3/-have relatively low d/sub eff/ values for infrared second harmonic generation (SHG), and efficient frequency doubling requires Ti:sapphire peak power levels in excess of 8 kW. Recently developed quasi-phase-matched (QPM) interactions in bulk materials such as periodically-poled lithium niobate (PPLN) offer significantly higher d,, values, opening the way for efficient ultraviolet generation from much lower power infrared lasers. SHG of 946 nm and 1064 nm Nd:YAG lasers in PPLN has recently been reported. Here we investigate ultraviolet generation by SHG of a 90 mW average power, 1.5 kHz repetition rate, injection-seeded Ti:sapphire laser in PPLN. Up to 19% conversion efficiency to 393 nm is achieved, despite the onset of ultraviolet absorption in PPLN.