Detailed spectroscopic characterization of Cr:ZnSe (Cr:ZnS) crystals under visible excitation into the charge transfer bands of Cr²⁺ impurities was performed. Middle infrared photoluminescence of Cr:ZnS under this excitation exhibits shorter rise time (~150ns) than that previously observed in Cr:ZnSe (~4-10 μs). As a result the quantum yield of Cr:ZnS mid-IR photoluminescence under 10ns pulsed 416nm excitation into the charge transfer band was estimated at close to 100%, which contrasts with low (~14%) quantum yield measured in Cr:ZnSe under 532nm pulsed excitation, indicating the possibility of efficient excitation of the upper laser level of Cr:ZnS using this mechanism. The rise time can be caused by cascade relaxation from higher lying levels through the ³T₁ metastable level, producing luminescence in the near-IR. Measurements of the temperature dependence of the middle- and near infrared photoluminescence signals are reported. These values indicated that more efficient pumping of Cr:ZnSe under 532nm excitation can be achieved at temperatures greater than 300 K. Results of high temperature laser experiments supporting this idea are presented.

Date Published: 26 March 2015
PDF: 6 pages
Proc. SPIE 9342, Solid State Lasers XXIV: Technology and Devices, 934225 (26 March 2015); doi: 10.1117/12.2180289

Published in SPIE Proceedings Vol. 9342:
Solid State Lasers XXIV: Technology and Devices
W. Andrew Clarkson; Ramesh K. Shori, Editor(s)