Calculation of the microscopic parameters of a self-induced transparency modelocked quantum cascade laser

A model to calculate the microscopic parameters of self-induced transparency (SIT) modelocked quantum cascade lasers (QCLs) is presented and the parameters are then calculated for a particular structure. These parameters are then used to calculate the gain to absorption ratio that is required to determine the required ratio of gain periods to absorbing periods that must be grown in order to obtain stable modelocked pulses. The modelocked pulse parameters, along with the stability limits are then calculated as the ratio of gain to absorption varies. For the SIT modelocked QCL design that we examined, we found that three to five gain periods must be grown for each absorbing period in order to ensure stable operation.