Abstract

Transition-metal-doped zinc chalcogenide crystals have recently been investigated as potential mid-IR lasers (L. D. DeLoach et al., IEEE J. Quantum Electron., accepted for publication.) Tetrahedrally-coordinated Cr²⁺ ions are especially attractive as lasants on account of high luminescence quantum yields for emission in the 2000 - 3000 nm range. ⁵E radiative lifetimes and emission cross sections are respectively ~10 psec and ~10⁻¹⁸ cm². The associated absorption band peaked at -1800 nm enables laser-diode pumping of the Cr²⁺ systems. Laser demonstrations with ZnS:Cr and ZnSe:Cr (using a MgF₂:Co²⁺ laser pump source) gave slope efficiencies up to 30%. Excited-state-absorption losses appear small, and passive losses dominate. Tuning experiments with a birefringent filter evidence a tuning range covering at least 2280 - 2530 nm. Cr-doped laser samples can be produced by Bridgman growth, seeded physical vapor transport, or diffusion doping.

© 1996 Optical Society of America