A grating structure for a grating coupler is provided which has a high efficiency resulting from the operating principle, is easily manufactured, and simultaneously has little reflection loss. This grating structure is provided with a core layer having periodic recesses and protrusions formed on the upper surface, a first upper cladding layer in contact with the upper surface of the core layer, a second upper cladding layer in contact with the upper surface of the first upper cladding layer, and a first lower cladding layer in contact with the lower surface of the core layer. The recessed portions of said recesses and protrusions are filled with the same material as the first upper cladding layer. The refractive index of the material forming the core layer is greater than the refractive index of the materials forming the first upper cladding layer, the second upper cladding layer and the first lower cladding layer. The refractive index of the material of the first upper cladding layer is greater than the refractive index of the material of the second upper cladding layer. The thickness from the upper surface of the protruding portions of the recesses and protrusions to the upper surface of the first upper cladding layer is within the range obtained by subtracting of the depth of the recesses and protrusions from ((2m.sub.11)/4) times (m.sub.1 being a positive integer) the wavelength, in the material forming the first upper cladding layer, of light inputted and outputted by the grating coupler.

Optical alignment of optical subassembly and optoelectronic device is achieved using an external source and an external receiver, passing optical signal through a passive waveguide in the optoelectronic device, via alignment reflective surface features provided on the optical subassembly. The optical subassembly is provided with a first alignment reflective surface directing alignment signal from the source to a grating coupler at the input of the waveguide, and a second alignment reflective surface directing to the receiver the alignment signal directed from a grating coupler at the output of the waveguide after the alignment signal has been transmitted from the input to the output through the waveguide. By adjusting the relative position between the optical subassembly and the optoelectronic device, and detecting the maximum optical power of the alignment signal reflected from the second alignment reflective surface, the position of best optical alignment of the optical subassembly and the optoelectronic device can be determined.

Optical alignment of optical subassembly and optoelectronic device is achieved using an external source and an external receiver, passing optical signal through a passive waveguide in the optoelectronic device, via alignment reflective surface features provided on the optical subassembly. The optical subassembly is provided with a first alignment reflective surface directing alignment signal from the source to a grating coupler at the input of the waveguide, and a second alignment reflective surface directing to the receiver the alignment signal directed from a grating coupler at the output of the waveguide after the alignment signal has been transmitted from the input to the output through the waveguide. By adjusting the relative position between the optical subassembly and the optoelectronic device, and detecting the maximum optical power of the alignment signal reflected from the second alignment reflective surface, the position of best optical alignment of the optical subassembly and the optoelectronic device can be determined.

An optical device includes: a light guide plate receiving, for each of N types of wavelength bands, a plurality of parallel light beams with different incident angles each corresponding to view angles, and guiding the received parallel light beams; a first and a second volume hologram gratings of reflection type having a diffraction configuration which includes N types of interference fringes each corresponding to the N types of wavelength bands, and diffracting/reflecting the parallel light beams. The optical device satisfies for each wavelength band, a relationship of P>L, where L represents a central diffraction wavelength in the first and second volume hologram gratings, defined for a parallel light beam corresponding to a central view angle, and P represents a peak wavelength of the parallel light beams.

An optical device includes: a light guide plate receiving, for each of N types of wavelength bands, a plurality of parallel light beams with different incident angles each corresponding to view angles, and guiding the received parallel light beams; a first and a second volume hologram gratings of reflection type having a diffraction configuration which includes N types of interference fringes each corresponding to the N types of wavelength bands, and diffracting/reflecting the parallel light beams. The optical device satisfies for each wavelength band, a relationship of P>L, where L represents a central diffraction wavelength in the first and second volume hologram gratings, defined for a parallel light beam corresponding to a central view angle, and P represents a peak wavelength of the parallel light beams.

There is provided a semi-circular resonator using a whispering gallery mode (WGM) and an optical sensor using the same. Accordingly, an active region that is a waveguide of an active layer in which laser oscillation is caused by gains of advancing beams is deeply etched in a semi-circular or semi-ring shape.

There is provided a semi-circular resonator using a whispering gallery mode (WGM) and an optical sensor using the same. Accordingly, an active region that is a waveguide of an active layer in which laser oscillation is caused by gains of advancing beams is deeply etched in a semi-circular or semi-ring shape.

Methods and systems for a bi-directional receiver for standard single-mode fiber based on grating couplers may include, in an integrated circuit comprising an optoelectronic transceiver, a multi-wavelength grating coupler, and first and second optical sources coupled to the integrated circuit: coupling first and second source optical signals at first and second wavelengths into the photonically-enabled integrated circuit using the first and second optical sources, where the second wavelength is different from the first wavelength, receiving a first optical data signal at the first wavelength from an optical fiber coupled to the multi-wavelength grating coupler, and receiving a second optical data signal at the second wavelength from the optical fiber. Third and fourth optical data signals at the first and second wavelengths may be communicated out of the optoelectronic transceiver via the multi-wavelength grating coupler.

Methods and systems for a bi-directional receiver for standard single-mode fiber based on grating couplers may include, in an integrated circuit comprising an optoelectronic transceiver, a multi-wavelength grating coupler, and first and second optical sources coupled to the integrated circuit: coupling first and second source optical signals at first and second wavelengths into the photonically-enabled integrated circuit using the first and second optical sources, where the second wavelength is different from the first wavelength, receiving a first optical data signal at the first wavelength from an optical fiber coupled to the multi-wavelength grating coupler, and receiving a second optical data signal at the second wavelength from the optical fiber. Third and fourth optical data signals at the first and second wavelengths may be communicated out of the optoelectronic transceiver via the multi-wavelength grating coupler.

Methods and systems for a chip-on-wafer-on-substrate assembly are disclosed and may include in an optical communication system comprising an electronics die and a substrate. The electronics die is bonded to a first surface of a photonic interposer and the substrate is coupled to a second surface of the photonic interposer opposite to the first surface. An optical fiber and a light source assembly are coupled to the second surface of the interposer in one or more cavities formed in the substrate. A continuous wave (CW) optical signal may be received in the photonic interposer from the light source assembly, and a modulated optical signal may be communicated between the optical fiber and photonic interposer. The received CW optical signal may be coupled to an optical waveguide in the photonic interposer using a grating coupler.