Femtosecond optical parametric amplifiers based on beta-barium borate crystals

Abstract

In this thesis we describe our experiments to construct and evaluate nondegenerate and degenerate optical parametric amplifiers (OP.-) based on betabarium borate (BBO) crystals. VVe used a mode-locked Titanium.Sapphire laser at a wavelength of 830 nm and a pulse duration of 140 fs. The Ti:Sapphire laser was frequency doubled with a type-I BBO crystal. The frequency doubled output of the laser was used to pump our OP.As. For 800 mVV’ of laser output, 300 mVV of maximum output power at the second harmonic was obtained, corresponding to a 38% conversion efficiency. Both type-I and type-II BBO crystals were used for parametric amplification. The type-II crystal resulted in a nondegenerate OPA due to the orthogonal polarizations of the signal and the idler beams. A degenerate OP.A was achieved with the type-I crystal. Phcise sensitive nature of the degenerate OPA, and phase insensitive nature of the nondegenerate OP.A were observed. The maximum gain of the degenerate OPA was measured to be 1.45, whereas the maximum gain of the nondegenerate OP.A was measured to be 1 .0 2 .