Optical study of CdSe _x S _l-x crystals doped with Cr

Solid-state broadband lasers emitting in the 2—4-μm region are of interest for a variety of applications. However, conventional lasers for these wavelengths have limitations, such as the complexity and cryogenic operation. Recently, alternative materials for the mid-IR lasers Crtdoped Il—VI chalcogenide crystals—have been proposed. The RT mid IR absorption in these crystals is due to the effective Cr2 intracenter transitions. We present the results of an investigation of the CdSeS1:Cr crystals. The crystals were grown from the CdSe source by seeded physical vapor transport in the helium atmosphere with a wafer of CdSeS1 as a seed. A CrSe source was used for the growth-time doping. The changing sulfur content along the growth axis was determined by energy dispersive x-ray microanalysis. An absorption peak in the IR range of 1.5—2.2 μm due to the Cr2 intracenter transition ⁵T₂ —> ⁵E of ions was revealed. The maximum peak absorption was determined to be 4.5 cm^-1. The concentration of the Cr2 ions in the samples calculated from the JR absorption was found to vary from 1 xlO' to 3x1018 cm3. With the sulfur content, the intracenter absorption peak shifts to shorter wavelengths.