We describe a high coupling-efficiency waveguide grating coupler for use in the optical interface between a planar multimode waveguide and a multimode optical fiber in mode division multiplexed optical communication systems. The multimode waveguide grating coupler can launch light from the different modes of the planar waveguide into the different modes of the multimode optical fiber and vice-versa. A silicon based multimode waveguide grating coupler was used to couple two polarizations of a multimode silicon waveguide into the LP01 mode and LP11 mode from a step index multi-mode fiber (MMF). Simulations of the preliminary design predicted the coupling efficiency to be −4.3 dB for LP01 mode and −5.0 dB for the LP11 mode. Experimental coupling efficiency of −4.9 dB and −6.1 dB were obtained for LP01 and LP11, respectively. The multiplexer can be passive.

An ultra-long sub-wavelength grating as an optical antenna for optical phased arrays includes a top structure and a bottom structure which are vertically stacked. The bottom structure is made of a material with a refractive index lower than a refractive index of the top structure. The top structure is made of a material with a refractive index higher than that of the bottom structure. A strip waveguide is disposed in the middle of the top structure. subwavelength blocks are disposed periodically on two sides of the straight strip waveguides. The invention has the following beneficial effects. The structure could increase the effective length of the grating; uniform near field distribution can be achieved by controlling the positions of the subwavelength blocks. The structure is simpler with lower fabrication requirements and lower cost.

This slow light waveguide includes an initial region which extends, along an optical axis, from a start starting from which the width of a central waveguide begins to continuously decrease up to an end beyond which the width of the central waveguide no longer decreases up to the end of a slowing section, this initial region overlapping a broadening region where the length of lateral teeth continuously increases, a final region which extends, along the optical axis, from a start starting from which the width of the central waveguide begins to continuously increase up to an end beyond which the width of the central waveguide no longer increases, this final region overlapping a narrowing region where the length of the lateral teeth continuously decreases.

A semiconductor structure including a semiconductor substrate, a first patterned dielectric layer, a grating coupler and a waveguide is provided. The semiconductor substrate includes an optical reflective layer. The first patterned dielectric layer is disposed on the semiconductor substrate and covers a portion of the optical reflective layer. The grating coupler and the waveguide are disposed on the first patterned dielectric layer, wherein the grating coupler and the waveguide are located over the optical reflective layer.

A semiconductor structure including a semiconductor substrate, a first patterned dielectric layer, a grating coupler and a waveguide is provided. The semiconductor substrate includes an optical reflective layer. The first patterned dielectric layer is disposed on the semiconductor substrate and covers a portion of the optical reflective layer. The grating coupler and the waveguide are disposed on the first patterned dielectric layer, wherein the grating coupler and the waveguide are located over the optical reflective layer.

A photonic interconnect apparatus includes tunable light devices, multiplexers to multiplex optical signals produced by the tunable light devices onto optical paths, and a cyclic arrayed waveguide grating (AWG) to receive the optical signals over the optical paths, and to direct a given optical signal of the received optical signals to a selected output of a plurality of outputs of the cyclic AWG based on a wavelength of the given optical signal. A respective demultiplexer directs the given optical signal to a selected output of a plurality of outputs of the respective demultiplexer according to which coarse wavelength band the wavelength of the given optical signal is part of.

An optical device for coupling light propagating between a waveguide and an optical transmission component is provided. The optical device including a taper portion and a grating portion. The grating portion is connected to the taper portion. The grating portion includes grating patterns. Ends of the grating patterns are separated from an outer edge of the optical device by a distance.

An optical device for coupling light propagating between a waveguide and an optical transmission component is provided. The optical device including a taper portion and a grating portion. The grating portion is connected to the taper portion. The grating portion includes grating patterns. Ends of the grating patterns are separated from an outer edge of the optical device by a distance.

A semiconductor device includes a photonic die and an optical die. The photonic die includes a grating coupler and an optical device. The optical device is connected to the grating coupler to receive radiation of predetermined wavelength incident on the grating coupler. The optical die is disposed over the photonic die and includes a substrate with optical nanostructures. Positions and shapes of the optical nanostructures are such to perform an optical transformation on the incident radiation of predetermined wavelength when the incident radiation passes through an area of the substrate where the optical nanostructures are located. The optical nanostructures overlie the grating coupler so that the incident radiation of predetermined wavelength crosses the optical die where the optical nanostructures are located before reaching the grating coupler.

A semiconductor device includes a photonic die and an optical die. The photonic die includes a grating coupler and an optical device. The optical device is connected to the grating coupler to receive radiation of predetermined wavelength incident on the grating coupler. The optical die is disposed over the photonic die and includes a substrate with optical nanostructures. Positions and shapes of the optical nanostructures are such to perform an optical transformation on the incident radiation of predetermined wavelength when the incident radiation passes through an area of the substrate where the optical nanostructures are located. The optical nanostructures overlie the grating coupler so that the incident radiation of predetermined wavelength crosses the optical die where the optical nanostructures are located before reaching the grating coupler.