Observation of birefringence induced by intersubband transitions in quantum wells

Abstract

We present a direct measurement of the birefringence induced by the intersubband transitions in quantum wells. Phase delays of up to 40°were observed in our samples, corresponding to a 0.07 difference in the index of refraction between the polarizations parallel and perpendicular to the plane of the wells in a GaAs/AlGaAs silicon-doped structure. The measurement was conducted at several wavelengths - enabling us to deduce the total linear birefringence near the absorption resonance. The observed birefringence is in close agreement with the Kramers-Kronig transform of the absorption spectra.