Tunneling influence on the intersubband optical absorption coefficient and refraction index in biased GaAs/AlGaAs quantum well wires

We investigate the tunnel effect influence on the intersubband optical absorption and refraction in a gallium arsenide quantum well wire in transverse electric field. The quasi-stationary energy levels and escape times are obtained using the complex eigenvalue study in a two-dimensional finite element method. The linear absorption coefficient and the relative change of the refractive index are calculated according to the Fermi's golden rule and by involving the intersubband relaxation time. Our work shows that the electronic linewidth broadening related to the carrier tunneling has a major effect on the optical absorption lines, especially for intense electric fields. Absorption peaks are blue-shifted by the increasing electric field and, at the same time, they are enlarged and decreased in amplitude. A field-invariable relaxation rate, as is assumed by many previous theoretical studies, could not be justified, even for moderate electric fields.