中国科学院重庆绿色智能技术研究院机构知识库

Nondegenerate two-photon absorption (ND-TPA) in a zinc blende-type ZnS single crystal has been investigated by using the ultrafast femtosecond pump-probe technique. ND-TPA coefficients for parallel and orthogonal polarization orientations have been determined at discrete probe wavelengths from 480 to 570 nm and a constant pump wavelength of 800 nm. The largest value of (6.40 +/- 0.76) cm/GW is found in the parallel case when probed at 480 nm, whereas the smallest value of (0.066 +/- 0.007) cm/GW appears in the orthogonal case when probed at 570 nm. Optimized scaling factors of 8126 and 4358 cm/GW eV(5/2) are proposed for better fitting the experimental dependence of the ND-TPA coefficient on the probe photon energy for the two polarization cases. Considering the intrinsic zinc blende symmetry and crystal orientation, the ND-TPA coefficients for the parallel and orthogonal polarization orientations are related to the imaginary part of two independent third-order susceptibility tensor elements chi(xxxx) and chi(xyxy), respectively. (C) 2013 Optical Society of America