2.3–2.7µm InGaAsSb/AlGaAsSb Broad-Contact and Single-Mode Ridge-Waveguide SCH-QW Diode Lasers Operating in CW Regime at Room Temperature

A new approach in the design of (Al)InGaAsSb/GaSb quantum well separate confinement heterostructure (QW-SCH) diode lasers has led to CW room-temperature lasing up to 2.7 gm. To avoid QW material degradation associated with the miscibility gap in the 2.3–2.7 tim wavelength range, we used highly strained, “quasi-ternary” InxGa1−xSbl−yAsy compounds with 0.25<x<0.38 and y<0.07 as the material for QWs. Very low threshold current density (∼300 A/cm2) and high CW output powers (>100 mW) were obtained from broad contact devices operating in the 2.3–2.6 μm wavelength range. From the spontaneous emission measurements we have identified that the Auger process determines the rate of recombination in quantum well active region over the entire temperature range studied (15– 110 'C) for 2.6 gim lasers and only at temperatures higher than 65 'C for 2.3 pim lasers. If Auger recombination dominates, strong temperature dependence of Auger coefficient leads to the rapid increase of threshold current density with temperature (To ∼40 °C). In the range of 15 – 65 °C for 2.3 gim devicesa monomolecular, non-radiative mechanism dominates and To is about 110 °C. In addition, single-mode CW room temperature ridge-waveguide lasers with wavelength of 2.3-2.55 gim have been fabricated for the first time. The lasers display threshold currents around 50 mA with CW output powers of several milliwatts. Since for a certain range of temperatures and currents one of the longitudinal modes dominates in the spectra of the ridge lasers they have been successfully applied forgas spectroscopy.