Performance comparison of optically pumped type-II midinfrared lasers

We report a comparative study on the performance of three optically pumped, type-II quantum well lasers with differing quantum well (QW) confinement. One of the active regions emphasized hole confinement, another emphasized electron confinement, while the third incorporated both electron and hole confinements. In all cases the wells were inserted in a thick InxGa1-xAsySb1-y waveguide/absorber region. The lasing wavelengths at 84 K were 2.26, 3.44, and 2.37 mu m, respectively. The maximum peak output powers and differential quantum efficiencies eta at 84 K were similar for the hole well and W lasers (approximate to 13 W,eta approximate to 0.55), but significantly reduced in the electron-well-only laser (2.3 W,eta=0.14). Waveguide loss measurements via the traditional quantum efficiency versus cavity length method and by a Hakki-Paoli method revealed that all three lasers had low waveguide loss that either increased slowly or not at all with increasing temperature. However, the laser's internal efficiency, eta(i), showed a linear decline with increasing temperature, with the eta(i) of the electron-well-only laser significantly less than the other two. The data suggest that for antimonide-based type-II designs, strong hole confinement is essential for improved performance. The data further suggest that it is hole leakage from the QW and/or hole dilution that is largely responsible for the degradation in laser performance. (c) 2005 American Institute of Physics.