US Patent 9829631 Vertical output couplers for photonic devices

A method forms a vertical output coupler for a waveguide that propagates light along a horizontal propagation direction, through a waveguide material that overlies a buried oxide layer. The method includes etching the waveguide to remove a portion of the waveguide. The etching forms at least a first plane that is at an edge of the waveguide, is adjacent to the removed portion of the waveguide, and is tilted at a vertical angle between 20 degrees and 70 degrees with respect to the propagation direction. The method further includes coating the first tilted plane with a reflective metal to form a mirror, such that the mirror reflects the light into a direction having a vertical component.