Self-focusing of 1aser beams is observed in Cd0.5Mn 0. 5 Τe at room temperature. The far-field patterns of laser beam after passing through the cad-mium manganese telluride crystal are investigated. The values of focal length as well as the absorption coefficient were measured as a function of intensity of laser radiation. From these measurements the values of nonlinear refrac-tive index for Cd0.5Mn0.5Te are determined. The results indicate that the self-focusing observed in Cd 1-x ΜnxTe is due to a thermally induced change in refractive index. PACS numbers: 42.65.Jx A well-known third-order nonlinear optical effect of great interest is the phenomenon of self-focusing of light. Self-focusing may occur when the refractive index of the nonlinear medium increases with the beam intensity, n = n0 + Δn, where Δn is the laser induced refractive index. and n 0 is the index of refraction for low intensity light. One of the most important physical mechanism responsible for Δn in semi-conduction is heating by CW laser beam with photon energies close to the band gap energy. It leads to dispersive nonlinearity induced by a shift of the band gap energy. In case of a laser beam with a Gaussian transverse profile propagating into the semiconductor with dn/dT > 0, the central part of the beam sees a larger refractive index than the edge. Consequently, the beam is focused by itself. Dis-persive nonlinearisty induced by a thermal shift of the band gap energy has been studied in several semiconductors [1]. In this paper the investigations of self-focusing of laser beam in Cd0.5Mn0.5Te is reported. It should be noticed that in Cd1-xMnxTe crystals with x > 0.5 the fundamental absorption is obscured by transitions within Mn++ ions [2]: Therefore,

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We present the results of optical and electrophysical investigations of CdTe:Cr crystals. A model explaining a considerable shift of the fundamental absorbtion edge in the crystals into the long-wave region is proposed. It is found that the doping of cadmium telluride crystals with Cr impurity leads to the introduction of deep donors with Е v + 0.19…0.32 eV.

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