Many-body optical gain of GaInNAs∕GaAs strained quantum-well lasers

Abstract

Optical properties of strained GaInNAs∕GaAs quantum wells (QWs) are investigated using the multiband effective-mass theory. We also take into account the many-body effects on the optical gain spectrum. It is observed that the transition energy decreases with increasing In or N mole fraction. The theoretical transition energies show very good agreement with the experimental results for several compositions and well widths. The optical gain is shown to increase with increasing compressive or tensile strain. The increase of the transverse electric optical gain is attributed to the fact that the subband energy spacing increases with the strain. On the other hand, the increase of the transverse magnetic optical gain is mainly due to the increases of the optical matrix element. The threshold current density rapidly decreases with increasing well width and begins to saturate near the well width of 80Å. In the case of a QW structure with relatively short cavity length (Lcav=800μm), it is found that the threshold current density is minimum near 80Å. We see that there is a universal relation governing the dependence of the band-gap renormalization on carrier density and the relation is close to ΔEg∝n2D1∕3.