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

摘要

We report the implementation of a KTP optical parametric oscillator pumped by a pulsed Ti:sapphire laser. Including signal and idler, it could be continuously tuned from 1.261 through 2.532 μm by varying the pump wavelength. Two major improvements were achieved, including the connection of the signal and idler tuning ranges and the high output pulse energy through the signal and idler tuning ranges. The first improvement was achieved by discovering two particular sets of phase-matching angles. The second improvement was realized by using five sets of resonator mirrors for oscillating either signal or idler. Theoretical calculations were also conducted for the effective nonlinear coefficient, walk-off angle, phase-matching acceptance angle, and output spectral widths for the concerned phase-matching angles. The second part of this paper presents the experimental and theoretical results of sum-frequency mixing (SFM) of a Ti:sapphire laser and a 1.064 μm Nd:YAG laser. By using two KTP crystals cut at θ=76°and 85°(ψ=90°in both crystals), respectively, we have experimentally achieved SFM tuning range from 459.3 through 472.9 nm. The energy conversion efficiencies were reasonably high.