Upconversion ultraviolet random lasing in Nd3+ doped fluoroindate glass powder

An upconversion random laser (RL) operating in the ultraviolet is reported for Nd3+ doped fluoroindate glass powder pumped at 575 nm. The RL is obtained by the resonant excitation of the Nd3+ state (2)G(7/2) followed by energy transfer among two excited ions such that one ion in the pair decays to a lower energy state and the other is promoted to state D-4(7/2) from where it decays emitting light at 381 nm. The RL threshold of 30 kW/cm(2) was determined by monitoring the photoluminescence intensity as a function of the pump laser intensity. The RL pulses have time duration of 29 ns that is 50 times smaller than the decay time of the upconversion signal when the sample is pumped with intensities below the RL laser threshold. (C) 2011 Optical Society of America