Kinetic theory of cascade laser based on quantum wells and wires

The numerical solution of a system of non-linear kinetic equations for electron distribution functions and non-equilibrium phonons is obtained for quantum cascade intersubband lasers on quantum wells and wires. In the case of quantum wells the analytical solution of system of equations is found. The possibility of lowering the threshold current as a result of the accumulation and reabsorption of optical phonons and due to different effective masses of electrons in subbands is demonstrated. For lasers on quantum wires the lowering of threshold current takes place also, with the rate being greater as for lasers on wells.