Decay of Raman active vibrations within oxide groups of potassium titanyl phosphate

Abstract

Decay of nine Raman active vibrations assigned to TiO6− and PO4− oxide groups of KTiOPO4 nonlinear-optical-gain crystal have been directly traced in time with <120 fs resolution. Coherent Anti-Stokes Raman scattering technique with three-color tunable femtosecond pulses provided detection of phonon decay transients with up to 70 dB signal spans and resulted in the equivalent spectral resolution of better than 0.15 cm−1. The equilibrium phonon decay rates ranged between 0.93 and 4.25 ps−1 yielding in the corresponding linewidths of 4.9–22.3 cm−1 for the homogeneously broadened vibrations.