Embodiments herein describe techniques for testing or aligning optical components in a photonic chip using a grating coupler. In one embodiment, the photonic chip may include an edge coupler and a grating coupler for optically coupling the photonic chip to external fiber optic cables. The edge coupler may be disposed on a side or edge of the photonic chip while the grating coupler is located on a top or side of the photonic chip. During fabrication, the edge coupler may be inaccessible. Instead of using the edge coupler to test the photonic chip, a testing apparatus can use the grating coupler along with a splitter to transfer optical test signals between an optical component in the photonic chip (e.g., a modulator or detector) and a test probe optically coupled to the grating coupler.

Embodiments herein describe techniques for testing or aligning optical components in a photonic chip using a grating coupler. In one embodiment, the photonic chip may include an edge coupler and a grating coupler for optically coupling the photonic chip to external fiber optic cables. The edge coupler may be disposed on a side or edge of the photonic chip while the grating coupler is located on a top or side of the photonic chip. During fabrication, the edge coupler may be inaccessible. Instead of using the edge coupler to test the photonic chip, a testing apparatus can use the grating coupler along with a splitter to transfer optical test signals between an optical component in the photonic chip (e.g., a modulator or detector) and a test probe optically coupled to the grating coupler.

In an example, an Echelle grating wavelength division multiplexing (WDM) device includes a first waveguide, a slab waveguide, multiple second waveguides, an Echelle grating, and a metal-filled trench. The first waveguide includes either an input waveguide or an output waveguide. The multiple second waveguides are optically coupled to the first waveguide through the slab waveguide. The multiple second waveguides include multiple output waveguides if the first waveguide includes the input waveguide or multiple input waveguides if the first waveguide includes the output waveguide. The Echelle grating includes multiple grating teeth formed in the slab waveguide. The metal-filled trench forms a mirror at the grating teeth to reflect incident light from the first waveguide toward the multiple second waveguides or from the multiple second waveguides toward the first waveguide.

Embodiments include a fiber to photonic chip coupling system including a collimating lens which collimate a light transmitted from a light source and an optical grating including a plurality of grating sections. The system also includes an optical dispersion element which separates the collimated light from the collimating lens into a plurality of light beams and direct each of the plurality of light beams to a respective section of the plurality of grating sections. Each light beam in the plurality of light beams is diffracted from the optical dispersion element at a different wavelength a light beam of the plurality of light beams is directed to a respective section of the plurality of grating sections at a respective incidence angle based on the wavelength of the light beam of the plurality of light beams to provide optimum grating coupling.

Embodiments include a fiber to photonic chip coupling system including a collimating lens which collimate a light transmitted from a light source and an optical grating including a plurality of grating sections. The system also includes an optical dispersion element which separates the collimated light from the collimating lens into a plurality of light beams and direct each of the plurality of light beams to a respective section of the plurality of grating sections. Each light beam in the plurality of light beams is diffracted from the optical dispersion element at a different wavelength a light beam of the plurality of light beams is directed to a respective section of the plurality of grating sections at a respective incidence angle based on the wavelength of the light beam of the plurality of light beams to provide optimum grating coupling.

A biochip device includes a waveguide, chromophore elements, a diffusing structure, and a sloping surface. The chromophore elements are disposed on a portion of the waveguide and are configured to emit fluorescence in response to excitation by guided light waves transmitted by the waveguide. The diffusing structure is configured to generate guided light waves in the waveguide when illuminated. The sloping surface is sloped relative to a plane of the waveguide and is configured to direct excitation light into the waveguide, and the sloping surface and the waveguide are configured to deflect the excitation light to the diffusing structure to generate guided light waves within the waveguide. The sloping surface may be a face of a prism attached to or integrated with the waveguide, or the sloping surface may be a bevel formed at an edge of the waveguide.

A biochip device includes a waveguide, chromophore elements, a diffusing structure, and a sloping surface. The chromophore elements are disposed on a portion of the waveguide and are configured to emit fluorescence in response to excitation by guided light waves transmitted by the waveguide. The diffusing structure is configured to generate guided light waves in the waveguide when illuminated. The sloping surface is sloped relative to a plane of the waveguide and is configured to direct excitation light into the waveguide, and the sloping surface and the waveguide are configured to deflect the excitation light to the diffusing structure to generate guided light waves within the waveguide. The sloping surface may be a face of a prism attached to or integrated with the waveguide, or the sloping surface may be a bevel formed at an edge of the waveguide.

A phase shift element includes a substrate and a dielectric ridge waveguide (DRW) disposed on the substrate. The DRW includes a dielectric material, and a width of the DRW is less than 500 nanometers (nm). A meta-grating includes a substrate and multiple dielectric ridge wave-guides (DRWs) disposed on the substrate.

A phase shift element includes a substrate and a dielectric ridge waveguide (DRW) disposed on the substrate. The DRW includes a dielectric material, and a width of the DRW is less than 500 nanometers (nm). A meta-grating includes a substrate and multiple dielectric ridge wave-guides (DRWs) disposed on the substrate.

Resonant-cavity infrared photodetector (RCID) devices that include a thin absorber layer contained entirely within the resonant cavity. In some embodiments, the absorber is a single type-II InAs-GaSb interface situated between an AlSb/InAs superlattice n-type region and a p-type AlSb/GaSb region. In other embodiments, the absorber region comprises quantum wells formed on an upper surface of the n-type region. In other embodiments, the absorber region comprises a W-structured quantum well situated between two barrier layers, the W-structured quantum well comprising a hole quantum well sandwiched between two electron quantum wells. In other embodiments, the RCID includes a thin absorber region and an nBn or pBp active core within a resonant cavity. In some embodiments, the RCID is configured to absorb incident light propagating in the direction of the epitaxial growth of the RCID structure, while in other embodiments, it absorbs light propagating in the epitaxial plane of the structure.