BEHAVIOR OF HOLE AND ELECTRON DOMINATED PHOTOREFRACTIVE CDTE-V CRYSTALS UNDER EXTERNAL CONTINUOUS OR PERIODIC ELECTRIC-FIELD

The photorefractive properties of two CdTe:V crystals are compared in the infrared range. For both crystals, an increase of the electron-hole competition factor (from electrons to holes) is measured when the operating wavelength increases. The values of the wavelength where the sign of the dominating carriers changes are different. In the high wavelength range, high TWM gains are obtained by applying a square-shaped electric field at an optimum frequency. This frequency dependence can be explained by considering the effect of a second deep level. In the low wavelength range, a resonant intensity-temperature effect, as in InP:Fe, is demonstrated for the first time in this material. The difference between the two crystals is assumed to be particularly sensitive to the compensation - or not - of the cadmium losses during the crystal growth.