Magnetic field effects on intersubband transitions in quantum cascade structures

Abstract

We report on our study of the effects of external magnetic field on the intersubband optical transitions in quantum cascade systems. We address the properties of two types of cascade structures: terahertz quantum cascade lasers and quantum dot infrared photodetectors. In both cases we study the optical properties of active regions of the systems: optical emission in the case of quantum cascade lasers and optical absorption in the case of photodetectors. The new features and new peaks in the optical spectra appear in the tilted magnetic field for quantum cascade lasers and in the parallel magnetic field for quantum dot photodetectors. In the relation to the possible spintronic application of cascade structures we study interplay of spin-orbit and magnetic field effects in cascade systems. If spin-orbit coupling is strong enough then at finite parallel magnetic field the optical emission spectra of quantum cascade lasers have two-peak structure.