Compensation of group velocity mismatch for optical parametric amplification in BBO type-I phase-matched configuration

Abstract

A method that compensates completely the group velocity mismatch between three w aves for femtosecond optical parametric amplification (OPA) in BBO type-I phase- matched configuration is presented by combining noncollinear configuration with tilting pump wave front. When the group velocities of the three waves are matche d, the variations of the noncollinear angle, the phase-matched angle and the pum p wave front tilt angle with the signal wavelength are calculated theoretically, and the effects of the pump beam size and the spatial walk-off length are analy zed. The results indicate that this method not only can achieve maximal parametr ic bandwidth, but also can match completely the group velocities between three w aves for femtosecond OPA. In addition, with increasing parametric gain, it is ve ry importance to appropriately choose the pump beam size and the nonlinear cryst al length.