Two-photon absorption in CdGa2S4 and CdGa2S3.96Se0.04 crystals

Two-photon absorption (TPA) measurements have been carried out in the chalcopyrite compounds CdGa2S4, CdGa2S3.96 Se-0.04 using single-wavelength excitation by a dye laser with lambda = 581 and 600 nm and pulse duration of 35 ps. Non-linear absorption coefficient for direct interband transitions has been measured in both crystals for E perpendicular to c and E parallel to c geometries by the non-linear transmittance method, TPA coefficients were found to be beta(perpendicular to) = (8.0 +/- 0.3) x 10(-9) cm/W, beta(parallel to) = (1.1 +/- 0.2) x 10(-8) cm/W and beta(perpendicular to) = (8.4 +/- 0.7) x 10(-9) cm/W, beta(parallel to) = (1.1 +/- 0.2) x 10(-8) cm/W for CdGa2S4 and CdGa2S3.96 Se-0.04 respectively. The experimental results are compared with the existing data for other chalcopyrite compounds. (C) 1999 Published by Elsevier Science B.V. All rights reserved.