Title :
Cr2+-doped zinc chalcogenides as efficient, widely tunable mid-infrared lasers
Author :
Page, Ralph H. ; Schaffers, Kathleen I. ; DeLoach, Laura D. ; Wilke, Gary D. ; Patel, Falgun D. ; Tassano, John B., Jr. ; Payne, Stephen A. ; Krupke, William F. ; Chen, Kuo-Tong ; Burger, Arnold
Author_Institution :
Lawrence Livermore Nat. Lab., CA, USA
fDate :
4/1/1997 12:00:00 AM
Abstract :
Transition-metal-doped zinc chalcogenide crystals have recently been investigated as potential mid-infrared lasers. Tetrahedrally coordinated Cr2+ ions are especially attractive as lasants on account of high luminescence quantum yields for emission in the 2000-3000-nm range. Radiative lifetimes and emission cross sections of the upper 5E state are respectively ~10 μs and ~10-18 cm2. The associated absorption band peaked at ~1800 mm 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 at present. Tuning experiments with a diffraction grating produce a tuning range covering at least 2150-2800 nm. Laser crystals can be produced by Bridgman growth, seeded physical vapor transport, or diffusion doping. Zinc chalcogenide thermomechanical properties of interest for medium-to-high-power operation compare favorably with those of other host materials, except for the larger refractive-index derivative dn/dT
Keywords :
II-VI semiconductors; chromium; crystal growth from melt; excited states; infrared sources; laser tuning; optical fabrication; optical materials; optical pumping; photoluminescence; radiative lifetimes; semiconductor lasers; 2000 to 3000 nm; 2150 to 2800 nm; Bridgman growth; Cr2+-doped Zn chalcogenides; MgF2:Co; ZnS:Cr; ZnSe:Cr; absorption band; diffraction grating; diffusion doping; emission cross sections; excited-state-absorption losses; lasants; laser-diode pumping; luminescence quantum yields; mid-infrared lasers; passive losses; radiative lifetimes; refractive index derivatives; seeded physical vapor transport; slope efficiencies; tetrahedrally coordinated ions; thermomechanical properties; transition-metal-doped Zn chalcogenide crystals; tuning experiments; tuning range; upper 5E state; widely tunable mid-infrared lasers; Absorption; Chromium; Crystals; Laser excitation; Laser theory; Laser transitions; Laser tuning; Luminescence; Pump lasers; Zinc;
Journal_Title :
Quantum Electronics, IEEE Journal of
