On the origin of bichromatic laser emission in Nd3+-doped fluoride glasses.

In this work we present a detailed study about the influence of the host matrix in the spectroscopic and laser properties of Nd3+ in three different fluoride glasses. Site-selective time-resolved techniques have been used to investigate the crystal field changes felt by the Nd3+ ion as a consequence of glass inhomogeneity. Stimulated emission experiments performed under selective wavelength laser pumping show the existence of bichromatic emission from two distinguishable site distributions for Nd3+ in fluoride glasses. This result can be explained by the moderate inter-site energy transfer among Nd3+ ions found in these systems.