Linear-circular dichroism of drag current due to nonlinear intersubband absorption of light in p-type Ge

A study has been made of the effect of the polarization state on linear absorption of radiation in the submillimeter range (λ = 90 μm) in p-type Ge crystals. The dependence of the current due to electron drag by photons on the intensity I of linearly and circularly polarized light has been measured. In both cases, it is observed that inversion of the photocurrent takes place with increasing intensity at I = 114 kW/cm 2 and I = 80 kW/cm 2 (at T = 300 K). The polarization dependences of the drag currents corresponding to two-photon transitions and the nonlinear current due to saturation of one-photon transitions are calculated. The theoretical results are then compared with experimental data, which makes it possible to identify the two contributions