GAIN TO ABSORPTION CONVERSION BY INCREASING EXCITATION DENSITY IN EXCITONIC WAVE-GUIDES

Exciton waveguiding was proposed to improve optical confinement of II- VI lasers. Strong resonant exciton absorption induces a refractive ind ex enhancement (An! on the low-energy side of the absorption peak. By stacking sheets of submonolayer (SML) CdSe insertions into a ZnSe matr ix, we fabricated a region in ZnSe with strong resonant exciton absorp tion. In this region, the k-selection rule is lifted due to exciton lo calization by the SML islands. Therefore, a zero-phonon lasing mechani sm resonant to the exciton waveguiding region could be realized. Using the variable-stripe-length method, we study the intensity-dependent o ptical gain of the ZnSe/CdSe submonolayer superlattices in a ZnS0.06Se 0.94 matrix. (C) 1998 Elsevier Science B.V. All rights resented.