## Abstract

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 $(6.40\pm 0.76)\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{cm}/\mathrm{GW}$ is found in the parallel case when probed at 480 nm, whereas the smallest value of $(0.066\pm 0.007)\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{cm}/\mathrm{GW}$ appears in the orthogonal case when probed at 570 nm. Optimized scaling factors of 8126 and $4358\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{cm}/\mathrm{GW}\text{\hspace{0.17em}}{\mathrm{eV}}^{5/2}$ 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.

© 2013 Optical Society of America

Full Article | PDF Article