Single-photon absorption of light and linear circular dichroism in gallium phosphide electronic conductivity

We interpret mechanism of occurrence of linear-circular dichroism intersubband nonlinear absorption of light in semiconductors with a "cone-shaped" zone structure, followed by single-photon optical transitions of carriers between the subzones located in the center of the Brillouin zone. According to the last relations, the probability of optical transitions with linearly polarized excitation is described by (7a, 8a), and in the case of excitation by circularly polarized light Formula (7b, 8b). This results in the alignment of the pulse of current carriers when illuminated with linearly polarized light. In the case where ( is photon wave vector) according to the law of conservation of angular momentum projection alignment occurs only moments for linear polarization. According (7 a, b), and (8 a, b) diagram direction in two planes and a vector containing spaces are not identical for the whole light. In the small light intensity, when the photo-induced changes in the distribution function of the carriers may be neglected, the directional pattern will be indistinguishable, and the likelihood of single-photon optical transitions do not depend on the degree of polarization.

According to (15) and (6) linearly factor circular dichroism in the range of high intensity, that is, does not depend on the intensity and equal . The frequency of the two-photon linear circular dichroism in semiconductors with a "cone-shaped" band structure occurs only when the account of the resonant saturation of the corresponding optical transitions and feature depending on the light intensity, as well as in single-photon nonlinear absorption.

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