| CPC H01S 5/2231 (2013.01) [C23C 14/30 (2013.01); H01L 21/31051 (2013.01); H01L 21/67098 (2013.01); H01L 21/68 (2013.01); H01S 5/0021 (2013.01); H01S 5/0202 (2013.01); H01S 5/0203 (2013.01); H01S 5/02461 (2013.01); H01S 5/0282 (2013.01); H01S 5/0425 (2013.01); H01S 5/1014 (2013.01); H01S 5/2202 (2013.01); H01S 5/2213 (2013.01); H01S 5/2214 (2013.01); H01S 5/343 (2013.01); H01S 5/04254 (2019.08); H01S 2301/176 (2013.01)] | 20 Claims |

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1. A laser structure, comprising:
a substrate;
an active region over the substrate;
a semiconductor layer over the active region, the semiconductor layer comprising a dovetail waveguide, the dovetail waveguide comprising a central top waveguide surface;
a metal layer extending over the semiconductor layer and contacting the central top waveguide surface a first air gap under the metal layer at a first side of the dovetail waveguide and a second air gap under the metal layer at a second side of the dovetail waveguide; and
an insulating layer over the semiconductor layer, under the metal layer, under the first air gap at the first side of the dovetail waveguide, and under the second air gap at the second side of the dovetail waveguide.
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