Retaining 3D shape of picosecond laser pulses during optical harmonics generation

Abstract

Collinear and noncollinear sum-frequency generation of broadband laser pulses with angular and frequency chirp is considered. The conditions of minimal distortions of 3D ellipsoidal intensity distribution of triangular chirped femtosecond pulses during generation of the second, third, and fourth harmonics of a Ti-Sa laser in LBO, BBO, and KBBF crystals are found using numerical methods. The efficiency of conversion from the fundamental to the fourth harmonic (45%) is higher than to the third harmonic (20%), and the distortions of intensity distribution are less.