Theoretical investigation of gain and linewidth enhancement factor for 1.55-μm tensile strained quantum-well lasers

The performance of quantum-well laser diodes with tensile strained wells was theoretically calculated. Using 4/spl times/4 Luttinger-Kohn Hamiltonian, valence band dispersion was calculated and used for the calculation of material gain. Linewidth enhancement factor was obtained by calculating the change of refractive index due to interband transition and free carrier plasma motion. The tensile well shows smaller material and differential gain compared to the compressive strained one. But smaller linewidth enhancement factor is obtained due to the absence of free carrier plasma effect. Linewidth enhancement factor is further reduced by p-type modulation doping in the barrier.