Enhanced absorption by stimulated emission in three excited states of Er3+ in yttrium aluminum garnet

Abstract

Using a laser diode modulated at 250 and 500 MHz, dependence of enhanced absorption on both sample length and temperature was investigated in an erbium doped yttrium aluminum garnet crystal. The transmitted laser intensity decreased with a decay time of 300 ps for sample lengths greater than 3.0 mm and temperatures higher than 50 K when the incident laser intensity increased. In addition, an emission peak was observed near 835 nm corresponding to the transition from the S3/24 level to the I13/24 in Er3+. It was suggested that the enhanced absorption was caused by stimulated emission in three excited states.