Native-oxide-confined high-index-contrast λ=1.15 μm strain-compensated InGaAs single quantum well ridge waveguide lasers

Abstract

High performance native-oxide-confined high-index-contrast (HIC) ridge waveguide (RWG) diode lasers are fabricated in a strain-compensated In0.4Ga0.6As single quantum well structure by employing a deep dry etch plus nonselective O2-enhanced wet thermal oxidation process. The thermal native oxide grown on the etch-exposed RWG sidewalls of the Al0.74Ga0.26As waveguide cladding layers and GaAs core with GaAsP–InGaAs quantum well provides both strong optical and electrical confinements for the active region. Due to a smoothing of sidewall roughness by the O2-enhanced oxidation, the lasers exhibit a low internal loss in αi=7.2 cm−1 for a w=7.2 μm narrow stripe HIC RWG structure, only 53% larger than that of w=87.2 μm broad-area devices, enabling their room temperature operation at a low 300 A/cm2 threshold current density.