Fiber alignment to photonics chip

A method of forming an optical system, comprising:

• forming a bridge layer over a semiconductor substrate, wherein the bridge layer comprises a waveguiding layer material;
• selectively etching the semiconductor substrate with respect to the bridge layer to form a cavity in the semiconductor substrate underlying the bridge layer, the cavity spatially separating the substrate from a bridge waveguide structure comprising the waveguiding layer material, wherein the bridge waveguide structure is laterally supported by the semiconductor substrate;
• forming a layer of composite adhesive within the cavity, wherein the composite adhesive includes a resin and air-filled pores dispersed throughout the resin;
• aligning an optical fiber with the bridge waveguide structure to transmit an optical signal thereto;
• and
• forming a non-composite adhesive between the bridge waveguide structure and an end portion of the optical fiber.

An optical system, comprising:

• a semiconductor substrate;
• a bridge waveguide structure comprising a waveguiding layer material, wherein the bridge waveguide structure is laterally supported by the semiconductor substrate and extends over and is spatially separated from a portion of the semiconductor substrate by a cavity in the semiconductor substrate;
• an optical fiber aligned with the bridge waveguide structure to transmit an optical signal thereto;
• a composite adhesive disposed within the cavity, wherein the composite adhesive includes a plurality of fibers of tungsten or molybdenum and a layer of resin overlying the plurality of fibers;
• and
• a non-composite adhesive disposed between the bridge waveguide structure and an end portion of the optical fiber.