SINGLE QUANTUM-WELL GAAS/ALGAAS SEPARATE CONFINEMENT HETEROSTRUCTURE LASERS WITH N-TYPE MODULATION DOPED CORES

Separate confinement heterostructure single quantum well GaAs/AlGaAs lasers with n-type modulation doped active regions are studied. Quantum well absorption is significantly modified by n-type modulation doping. The effects of modulation doping on transparency current density and threshold current density are determined. Modulation doping is shown to reduce transparency current density, thereby also reducing threshold current density. Threshold current densities are reduced by 30%, to values of less than 150 A/cm2 for long cavities. The effects on distributed loss and differential gain are also reported. No degradation of laser performance is observed due to the location of the electrical junction away from the active region or due to free carrier absorption loss. Heavily modulation doped structures lase on the second quantized state.