Self-aligned single-lateral-mode waveguide diode ring lasers

The majority of semiconductor ring lasers reported to date, have been formed by etching the waveguide through the entire active region, which results in multi-lateral mode operation. In order to make single-lateral-mode ring lasers with etched facets, the waveguide and the facet have to be etched separately, with the facet deep etched, but the waveguide shallow etched.<>