Control of electron-optical-phonon scattering rates in quantum box cascade lasers

Electron scattering with longitudinal-optical phonons is the main energy relaxation process between two-dimensional states in semiconductor heterostructures. This effect can be modified when the electron dispersion is broken into series of discrete states, similar to the energy spectrum of quantum boxes. This has been verified by applying a magnetic field parallel to the current of a quantum cascade laser. Light intensity as a function of the magnetic field shows pronounced oscillations, in excellent agreement with our calculations of the electron-phonon scattering rates between Landau levels.