TEA CO2 laser radiation induced EMF’s in tellurium

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Abstract
A comprehensive set of measurements is presented with the purpose of obtaining and interpreting all tensor components necessary to describe the fast emf’s induced in intrinsic and extrinsic single‐crystal tellurium samples exposed to TEA CO2 laser radiation in the range between 115 and 300 K. Three distinct mechanisms for the generation of the fast signals have been identified, namely, the fourth‐rank tensorial photon drag effect, a third‐rank tensorial optical rectification effect dependent on the carrier type and concentration, and a spurious signal predominant only at low temperatures in structurally imperfect crystals. The experimental results show that, for the photon drag effect, the important tensorial coefficients relating the induced electric field to the incident laser power density are T*1133=T*2233 with room‐temperature values in undoped and extrinsic crystals respectively equal to 0.85×10−7 and 1.1 ×10−7 cm/A. The values of the finite third‐rank tensor components χ*122=χ*212=χ*111 are correspondingly obtained to be 0.25×10−7 and 0.7×10−7 cm/A. Finally, the magnitude of the low‐temperature spurious signal is found to vary from sample to sample with maximum values attained at lowest temperatures ranging from essentially zero to in excess of 3 V/MW cm−2, depending on the sample used. The results concerning the photon drag effect are found to be consistent with the theory, and the third‐rank tensorial signal is ascribed to a nonlinear conductive behavior in the material.

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