A quantum cascade laser using a native-oxide-defined current aperture and optical waveguide

Summary form only. The long wavelength of quantum cascade (QC) lasers mediates against good confinement of the optical mode to the waveguide core and so a thick, 'plasma-enhanced' waveguide is normally used. We report a fabrication technique which provides electrical and optical confinement by conversion (rather than removal) of the Al/sub 0.48/In/sub 0.52/As upper cladding to a native oxide. In this technique, planar (vertical) selective thermal wet oxidation (PSWOX), the oxidation reaction begins at the AlInAs surface and proceeds downwards through the semiconductor using H/sub 2/O to convert the AlInAs into an oxide mainly composed of amorphous matrix (AlO/sub x/, As), with crystallised In/sub 2/O/sub 3/.