High-Index-Contrast λ = 1.55 μm AlInGaAs/InP Laser Heterostructure Waveguides Through Selective Core Oxidation

A deep-etched high-index-contrast ridge waveguide for low bend loss photonic integration is realized through selective lateral oxidation of a λ = 1.55 µm AlInGaAs multi-quantum well diode laser heterostructure waveguide core layer sandwiched between InP cladding layers. The process is enabled by first depositing a thin protective layer to fully suppress the thermal dissociation of exposed InP surfaces during the subsequent oxygen-enhanced wet thermal oxidation process. Either ≈30–100 nm of InGaAs grow through selective epitaxial regrowth via MOCVD or ≈6 Å of HfO₂ grows via atomic layer deposition is found to be effective at preventing dissociation damage. A lateral oxidation depth of ≈1.0 µm is achieved with a 3 h oxidation at 525 °C, yielding a buried oxide high optical confinement waveguide with reduced capacitance and contact resistance, suitable for the integration of high-speed, low-bend loss integrated laser devices.