Disclosed are grating couplers having a high coupling efficiency for optical communications. In one embodiment, an apparatus for optical coupling is disclosed. The apparatus includes: a substrate; a grating coupler comprising a plurality of coupling gratings over the substrate, wherein each of the plurality of coupling gratings extends in a first lateral direction and has a cross-section having a middle-raised shape in a second lateral direction, wherein the first and second lateral directions are parallel to a surface of the substrate and perpendicular to each other in a grating plane; and a cladding layer comprising an optical medium, wherein the cladding layer is filled in over the grating coupler.

Disclosed are grating couplers having a high coupling efficiency for optical communications. In one embodiment, an apparatus for optical coupling is disclosed. The apparatus includes: a substrate; a grating coupler comprising a plurality of coupling gratings over the substrate, wherein each of the plurality of coupling gratings extends in a first lateral direction and has a cross-section having a middle-raised shape in a second lateral direction, wherein the first and second lateral directions are parallel to a surface of the substrate and perpendicular to each other in a grating plane; and a cladding layer comprising an optical medium, wherein the cladding layer is filled in over the grating coupler.

A three-dimensional photonic integrated structure includes a first semiconductor substrate and a second semiconductor substrate. The first substrate incorporates a first waveguide and the second semiconductor substrate incorporates a second waveguide. An intermediate region located between the two substrates is formed by a one dielectric layer. The second substrate further includes an optical coupler configured for receiving a light signal. The first substrate and dielectric layer form a reflective element located below and opposite the grating coupler in order to reflect at least one part of the light signal.

A three-dimensional photonic integrated structure includes a first semiconductor substrate and a second semiconductor substrate. The first substrate incorporates a first waveguide and the second semiconductor substrate incorporates a second waveguide. An intermediate region located between the two substrates is formed by a one dielectric layer. The second substrate further includes an optical coupler configured for receiving a light signal. The first substrate and dielectric layer form a reflective element located below and opposite the grating coupler in order to reflect at least one part of the light signal.

In an example, a photonic system includes a Si PIC with a Si substrate, a SiO.sub.2 box formed on the Si substrate, a first layer, and a second layer. The first layer is formed above the SiO.sub.2 box and includes a SiN waveguide with a coupler portion at a first end and a tapered end opposite the first end. The second layer is formed above the SiO.sub.2 box and vertically displaced above or below the first layer. The second layer includes a Si waveguide with a tapered end aligned in two orthogonal directions with the coupler portion of the SiN waveguide such that the tapered end of the Si waveguide overlaps in the two orthogonal directions and is parallel to the coupler portion of the SiN waveguide. The tapered end of the SiN waveguide is configured to be adiabatically coupled to a coupler portion of an interposer waveguide.

In an example, a photonic system includes a Si PIC with a Si substrate, a SiO.sub.2 box formed on the Si substrate, a first layer, and a second layer. The first layer is formed above the SiO.sub.2 box and includes a SiN waveguide with a coupler portion at a first end and a tapered end opposite the first end. The second layer is formed above the SiO.sub.2 box and vertically displaced above or below the first layer. The second layer includes a Si waveguide with a tapered end aligned in two orthogonal directions with the coupler portion of the SiN waveguide such that the tapered end of the Si waveguide overlaps in the two orthogonal directions and is parallel to the coupler portion of the SiN waveguide. The tapered end of the SiN waveguide is configured to be adiabatically coupled to a coupler portion of an interposer waveguide.

Systems, devices, and methods of manufacturing optical engines and laser projectors that are well-suited for use in wearable heads-up displays (WHUDs) are described. Generally, the optical engines of the present disclosure integrate a plurality of laser diodes (e.g., 3 laser diodes, 4 laser diodes) within a single, hermetically or partially hermetically sealed, encapsulated package. A grating waveguide combiner comprising a plurality of waveguides having grating couplers thereon may be used to combine beams of light emitted by the plurality of laser diodes into a coaxially superimposed aggregate beam. Such optical engines may have advantages over existing designs including, for example, smaller volumes, better manufacturability, faster modulation speed, etc. WHUDs that employ such optical engines and laser projectors are also described.

Systems, devices, and methods of manufacturing optical engines and laser projectors that are well-suited for use in wearable heads-up displays (WHUDs) are described. Generally, the optical engines of the present disclosure integrate a plurality of laser diodes (e.g., 3 laser diodes, 4 laser diodes) within a single, hermetically or partially hermetically sealed, encapsulated package. A grating waveguide combiner comprising a plurality of waveguides having grating couplers thereon may be used to combine beams of light emitted by the plurality of laser diodes into a coaxially superimposed aggregate beam. Such optical engines may have advantages over existing designs including, for example, smaller volumes, better manufacturability, faster modulation speed, etc. WHUDs that employ such optical engines and laser projectors are also described.

Systems, devices, and methods of manufacturing optical engines and laser projectors that are well-suited for use in wearable heads-up displays (WHUDs) are described. Generally, the optical engines of the present disclosure integrate a plurality of laser diodes (e.g., 3 laser diodes, 4 laser diodes) within a single, hermetically or partially hermetically sealed, encapsulated package. Photonic integrated circuits having grating or edge couplers thereon may be used to wavelength multiplex beams of light emitted by the plurality of laser diodes into a coaxially superimposed aggregate beam. A waveguide medium having one or more directly written waveguides may couple light from laser diodes to a photonic integrated circuit, and may optionally hermetically or partially hermetically seal the laser diodes, eliminating the need for a separate seal. Such optical engines may have advantages over existing designs including, for example, smaller volumes, better manufacturability, faster modulation speed, etc. WHUDs that employ such optical engines and laser projectors are also described.

Systems, devices, and methods of manufacturing optical engines and laser projectors that are well-suited for use in wearable heads-up displays (WHUDs) are described. Generally, the optical engines of the present disclosure integrate a plurality of laser diodes (e.g., 3 laser diodes, 4 laser diodes) within a single, hermetically or partially hermetically sealed, encapsulated package. Photonic integrated circuits having grating or edge couplers thereon may be used to wavelength multiplex beams of light emitted by the plurality of laser diodes into a coaxially superimposed aggregate beam. A waveguide medium having one or more directly written waveguides may couple light from laser diodes to a photonic integrated circuit, and may optionally hermetically or partially hermetically seal the laser diodes, eliminating the need for a separate seal. Such optical engines may have advantages over existing designs including, for example, smaller volumes, better manufacturability, faster modulation speed, etc. WHUDs that employ such optical engines and laser projectors are also described.