intersubband pumping of an : InP symmetric double quantum well terahertz laser

The feasibility of intersubband optical excitation of a terahertz (1–10 THz) or far-infrared (30–300 ) emitter/laser by a laser diode is investigated by means of envelope function/effective mass approximation and subband carrier lifetime calculations. The material system is employed in order to supply the necessary conduction band offset and the basic design is that of a 6-level symmetric double quantum well. This can simultaneously satisfy the criteria of an 800 meV intersubband absorption and a far-infrared emission. It is shown that these device designs can satisfy a necessary criterion for population inversion at room temperature. A scheme for improving the population ratio based on a 9-level triple quantum well is discussed.