GAIN WITHOUT INVERSION IN INTERBAND-TRANSITIONS OF SEMICONDUCTOR QUANTUM-WELLS FROM A SINGLE-PARTICLE PERSPECTIVE

The quantum interferences arising in three-level atomic systems are in vestigated in analogous asymmetric semiconductor quantum well structur es. These investigations lead to the conditions necessary for induced zero absorption and gain without population inversion in interband tra nsitions. Asymmetric quantum well configurations are proposed and anal yzed for induced zero absorption and gain without inversion using a si ngle particle density-matrix approach. This density-matrix approach is described and shown to give the steady-state solutions for absorption and gain without the approximations required for perturbative or iter ative methods. Both excitonic and continuum transitions are examined u sing typical semiconductor parameters with excitonic transitions contr ibuting the largest fraction of gain without inversion. While interban d transitions differ from intraband and atomic transitions, results fo r the proposed quantum well configurations validate the basic concept of inversionless gain in semiconductors and point the way to ultralow threshold semiconductor microlasers.