Pump-tuning optical parametric oscillation and sum-frequency mixing with KTP pumped by a Ti : sapphire laser

We report the implementation of a KTP optical parametric oscillator pumped by a pulsed Ti:sapphire laser. Including signal and idler, it could be cont inuously tuned from 1.261 through 2.532 mum by varying the pump wavelength. Two major improvements were achieved, including the connection of the sign al and idler tuning ranges and the high output pulse energy through the sig nal and idler tuning ranges. The first improvement was achieved by discover ing two particular sets of phase-matching angles. The second improvement wa s realized by using five sets of resonator mirrors for oscillating either s ignal or idler. Theoretical calculations were also conducted for the effect ive nonlinear coefficient, walk-off angle, phase-matching acceptance angle, and output spectral widths for the concerned phase-matching angles. The se cond part of this paper presents the experimental and theoretical results o f sum-frequency mixing (SFM) of a Ti:sapphire laser and a 1.064 mum Nd:YAG laser. By using two KTP crystals cut at theta = 76 degrees and 85 degrees ( psi = 90 degrees in both crystals), respectively, we have experimentally ac hieved SFM tuning range from 459.3 through 472.9 nm. The energy conversion efficiencies were reasonably high. (C) 2001 Published by Elsevier Science B .V.