ANISOTROPY OF 2-PHOTON ABSORPTION IN CUBIC DIRECT-BAND-GAP SEMICONDUCTORS

The two-photon absorption (TPA) cross section in zinc-blende-structure semiconductors has been analyzed, both analytically and numerically. The warping of the valence band is shown to result in a dependence of the TPA on the orientation of the polarization plane of the light with respect to the crystal axes, i.e., in a linear dichroism. In InSb and GaAs, the relative differences in the TPA cross sections for light polarized along <100> and <111> axes, depending on the light wavelength, are 0.02-0.05 and 0.13-0.20, respectively. The linear-circular dichroism of TPA, even in narrow-band-gap semiconductors, is noticeably influenced by the presence of a split-off valence subband.