Theoretical analysis of gain saturation coefficients in InGaAs/AlGaAs strained layer quantum well lasers

Abstract

The gain saturation coefficient ε of InGaAs/AlGaAs strained layer quantum well lasers (SL‐QWLs) is calculated as a function of strain from intrasubband relaxation times. The intrasubband relaxation times are in turn obtained within the random phase approximation (RPA) including carrier‐carrier as well as carrier‐polar optical phonon interactions. The band structures are included by using the Luttinger–Kohn Hamiltonian [Phys. Rev. 97, 869 (1955)] and a multiband effective mass equation. It is demonstrated that the gain saturation coefficient increases with compressive strain in the active layer of quantum wells due to a corresponding increase of the intrasubband relaxation time.