Abstract

We investigated two types of structures. They had 150 QWs, surface concentration n_s = 2 × 10¹¹ cm^–2 but different wide of QW (Fig. la,b). In case "a" there was one energy level in QW and light absorption was caused by the transitions of electrons from ground state ϵ₁ to the continuous energy spectrum or to the resonance state connected with the size quantization level in the barrier. In the case "b" the light absorption was appeared due to transitions between levels of size quantization in QW ϵ₁ and ϵ₂. The spectral dependence of light absorption for two polarization-active, including e_ω||OZ component and passive, where e_ω⊥OZ– have been studied. To increase the length of interaction between the light and QW, the sample was made diamond-shaped to provide the multiple total internal reflection. The strong electric field was applied along the layers. The light absorption peak for polarization e_ω||OZ was near the wavelength λ = 11 µm. The modulation of light, including CO₂-laser radiation, under the heating of electrons in strong electric field E > 1 kV/cm, applied along the layers, have been investigated. It sharply differed for two polarizations (Fig. 2). Model explained the dependence of light modulation from the electric field was suggested.

© 1995 IEEE