Using a multiobjective evolutionary algorithm to develop a quantum cascade laser operating in the terahertz frequency range

Quantum cascade laser (QCL) is a specific type of semiconductor laser that operates through principles of quantum mechanics. Because there is a genuine lack of compact and coherent devices which can operate in the far-infrared region the motivation exists for designing a terahertz (THz) QCL. To ensure operation in the THz region the device must conform to the extremely small energy level spacing. The time and expense of the design and production process is prohibitive, so an alternative to fabrication was necessary. The overarching goal of this innovative research is to find QCL parameter combinations which can be used to fabricate viable structures. To accomplish this goal a model was developed at Worcester Polytechnic Institute with sponsorship from the Air Force Research Laboratory Sensors Directorate. A general multiobjective parallel evolutionary algorithm (GenMOP), developed at the Air Force Institute of Technology, was integrated to form a computer simulation which stochastically searches for feasible solutions. Although suitable solutions are found for certain frequencies, a challenge is presented because the search space suggests a limited set of discrete solutions with fewer being feasible.