Vibrational linewidths and dephasing of H− local modes in disordered calcium fluoride

The local mode lineshape for substitutional H− ions in CaF2 shows a broadened, two peak structure when La3+ co-doping up to 6 mol% is included. Pump-probe measurements of the local mode lifetime show a decrease in the anharmonic decay rate as a function of disorder. This phenomenon appears well correlated with four-wave mixing measurements which display a multiexponential behaviour having long lasting components with a homogeneous dephasing time greater than 90 ps.