Anomalously delayed stimulated emission in random lasers

Abstract

In a random laser based on a mixture of ${\mathrm{Nd}}^{3+}:{\mathrm{Ba}}_{5}$(${\mathrm{PO}}_{4}$)${}_{3}$ and ${\mathrm{Cr}}^{4+}:{\mathrm{Y}}_{3}$${\mathrm{Al}}_{5}$${\mathrm{O}}_{12}$ powders, we have observed trains of anomalously delayed stimulated emission pulses, which lasted for several tens of nanoseconds after the end of the pumping pulse. The phenomenon is explained by the color-center formation and reversed-saturable absorption in ${\mathrm{Cr}}^{4+}$:YAG powder.