ANALYSIS OF REDUCED INTERBAND ABSORPTION MECHANISMS IN SEMICONDUCTOR QUANTUM-WELLS

Mechanisms for reduced interband absorption using intersubband coheren ce or intersubband coupling in semiconductor quantum wells are analyze df by exactly solving the density matrix equation. By placing some mil d limitations on the diagonal density matrix elements, general analyti c solutions are obtained without weak-field restrictions. Our solution s demonstrate reduced absorption, various nonlinear processes, and cou pling-field-modulation of interband transitions. Our results agree wel l with previous results for three-level atomic systems, give insights into nonlinear mechanisms, and point out the importance of nonperturba tive approaches to this class of problems.