INFLUENCES OF UNCONFINED STATES ON THE OPTICAL-PROPERTIES OF QUANTUM-WELL STRUCTURES

The population of the unconfined states, with energies above the band edge of the barrier layers, can be significant in some regions of the active volume in high power lasers and amplifiers, This paper analyzes the influences of these states on optical properties, such as gain, r efractive index, differential gain, and linewidth enhancement factor, for different quantum-well (QW) structures, Our results show that at h igh excitation levels, the unconfined band contributions to the real p art of the optical susceptibility can be significant, especially in st ructures with weak quantum confinement potentials, This is in agreemen t with recent measurements of peak gain and carrier-induced refractive index change versus carrier density, for InGaAs-GaAs QW laser structu res.