Possibility of room temperature intra-band lasing in quantum dot structures placed in high-photon density cavities

Abstract

We study the possibility of room temperature intraband lasing in quantum dots placed in high-photon density cavities. In general, if intra-band population inversion is to created in a quantum well by carrier injection at the barrier energy, it is necessary that the electron intra-band energy relaxation times are long. Additionally the bandedge electron-hole recombination times should be short. The use of sub-two-dimensional structures (quantum dots) allows us to increase the intra-band energy relaxation time from about a picosecond for bulk or quasi-two-dimensional systems to several hundred picoseconds at room temperatures. Also, by placing these structures in a high coherent photon density optical cavity, it is possible to decrease the bandedge electron-hole recombination times through stimulated emission. Our studies show that strong population inversion is possible at room temperature in such systems. Gain versus injection curves are also calculated.