Properties of strained (In, Ga, Al)As lasers with laterally modulated active region

Transmission electron microscopy studies of low indium composition InxGa1−xAs insertions (x<0.4) in a GaAs matrix deposited by molecular beam epitaxy or by metal-organic chemical vapor deposition reveal nanoscale quasiperiodic compositional and morphological modulations. The luminescence peak wavelength is found to be a strong function of deposition parameters and can be tuned from 1.1 to 1.3 μm for the same x and average thickness of the deposit. Strained (In, Ga, Al)As lasers with such a laterally modulated InxGa1−xAs active region demonstrate significant depolarization of the electroluminescence. For short cavity length, lasing occurs at energies corresponding to transitions between InxGa1−xAs conduction band and light holelike valence band states. Devices lase at low threshold current densities and demonstrate continuous wave operation up to 3 W at room temperature.