Influence of active ion concentration on fluorescence efficiency and lasing performance in Cr2+:ZnSe lasers

This work investigates the effect of Cr²⁺ concentration on the fluorescence lifetime, fluorescence efficiency, and lasing performance in Cr²⁺:ZnSe lasers. Polycrystalline Cr²⁺:ZnSe samples with varying chromium concentration (averages between 0.34×10¹⁸ and 66.2×10¹⁸ cm^-3) are prepared by diffusion doping. Lasing experiments are performed by using a KTP OPO operating at 1570 nm. The best power performance is obtained with a Cr²⁺:ZnSe sample containing an estimated Cr²⁺ ion concentration of 14.1×10¹⁸ cm^-3. Experimental data showing the dependence of the pulse build-up time and output pulsewidth on pump energy, ion concentration, and output coupler transmission are also discussed during the presentation.