Abstract

To maximize the energy storage capacity of neodymium doped laser media it is necessary to choose materials characterized by a long fluorescence lifetime, which allows for efficient integration and storage of pump energy provided by flashlamp pulses of long duration (~1 ms). The low cross section for stimulated emission associated with a long fluorescence lifetime is also useful for suppression of amplified spontaneous emission (ASE). When the fluorescence lifetime is long, however, competition between the radiative and nonradiative decay processes becomes more important. In particular, multiphonon emission from the upper laser level establishes an absolute lower limit to the decay rate of the excited states and an upper limit to the fluorescence lifetime in any given material. We report for the first time we believe, the experimental determination of multiphonon emission rates in several neodymium doped laser media which exhibit long fluorescence lifetimes. These include the silicate laser glasses, LG-650 and LG-660,¹ along with the fluorite crystals SrF₂ and BaF₂.

© 1990 Optical Society of America