Control of gain and amplification in random lasers

Abstract

We have studied the competition between the ${}^{4}F_{3∕2}\to {}^{4}I_{11∕2}$ and ${}^{4}F_{3∕2}\to {}^{4}I_{13∕2}$ gain channels in the $\mathrm{Nd}:{\mathrm{Ba}}_5({\mathrm{PO}}_4{)}_3\mathrm{F}$ random laser. The strength of stimulated emission transitions was influenced by adding to the Nd-doped powder the powder of ${\mathrm{Cr}}^{4+}:{\mathrm{Y}}_3{\mathrm{Al}}_5{\mathrm{O}}_{12}$, absorbing light at $\lambda =1.06\mathrm{\mu }\mathrm{m}$, and the $1.32\mathrm{\mu }\mathrm{m}$ mirror, which provided an extra stimulated emission feedback. We have demonstrated a robustness of the Nd random laser to contamination. A much better control of the spectrum of the stimulated emission can be obtained by means of wavelength-selective external mirrors.

© 2007 Optical Society of America