Demonstration of high-efficiency, high-average-power second-harmonic generation in multi-pass quadrature arrangement using CsLiB/sub 6/O/sub 10/ crystals

Summary form only given. We propose a multi-pass quadrature arrangement aiming to generate high-energy and high-average-power green output with high conversion efficiency for pumping high-peak-power, ultrashort pulse Ti:sapphire laser amplifiers. The type II crystals were arranged so that the second-harmonic beams generated in them are orthogonally polarized (Eimerl, IEEE J. Quantum Electron. 23, 1361-1371, 1987). In this quadrature arrangement, the conversion efficiency is much less sensitive to the fundamental laser pulse nonuniformities than in a single crystal method and the second-harmonic beam generated in the first crystal does not interact with the fundamental beam in the second. The fundamental laser beam was passed through the quadrature arrangement up to four times using polarization rotation. In the two pass case, the mirror is removed, and the beam dumped.