Spectral Dynamics of a Diffusive Random Laser Under Two-Photon Pumping

Abstract

The spectral dynamics of a diffusive random laser under two photon excitation is investigated by using an experimental set-up which allows for fine mode discrimination and time resolution. The diffusive scattering system consists of a di-ureasil hybrid matrix powder doped with Rhodamine B. The anti-Stokes random laser emission obtained by pumping at 1064 nm shows a larger output pulse duration, build-up time, and threshold than the one produced under one photon pumping at 532 nm using the same experimental conditions. The time resolved analysis of the single shot emission pulse demonstrates the inherent stochastic nature of its lasing modes as well as the existence of modal relaxation oscillations. The outcome of our experiments also suggests that mode saturation appears with the increase of pump power.