Lasing in spin-polarized terahertz quantum cascade structures

We investigate theoretically the possibility of lasing in the terahertz in a suitably designed quantum cascade structure comprising dilute magnetic semiconductors, quantum cascade laser. Tunability is based on the spin-dependent potential induced by a magnetic field. The Boltzmann equation approach was used in order to predict the dependence of the gain and current on magnetic and electric fields. The electron dynamics were modeled by taking electron-longitudinal optical phonon, electron-longitudinal acoustic phonon and electron-electron scattering into account. Tunability of the emission energy between 10 meV and 26 meV, and 38 meV and 42 meV, for transitions of spin-down and spin-up electrons respectively, may be achieved by varying a magnetic field up to 5 T, at a temperature of 1.5 K. Comparison of the calculated optical gain, and losses in the appropriate waveguide, indicates the prospect of achieving laser operation.