Abstract

Q-switching in semiconductor lasers is not as efficient as in solid-state lasers, such as Nd:YAG lasers, because of the rapid depletion of the population inversion by the strong spontaneous emission and other higher-order nonradiative recombination processes. Recent studies of the carrier lifetime in GaAs¹ and InGaAs quantum-well lasers reveal that the carrier lifetime can be prolonged by the storage of a portion of the carriers in the continuum states of the confinement layers, in which the carrier volume density is diluted and the overall carrier lifetime is prolonged. Thus, the confinement layers behave like a carrier reservoir. This allows the population inversion to build up to a much higher level in a tailored structure for Q switching or pulse amplification. We will present a theoretical analysis that shows that the carrier storage can be achieved with minimal reduction in the gain coefficient of the quantum well. The maximum energy that can be stored and the speed limit imposed by the carrier capture rate will also be discussed.

© 1990 Optical Society of America