A multi-path interference filter. The multi-path interference filter includes a first port waveguide, a second port waveguide, and an optical structure connecting the first port waveguide and the second port waveguide. The optical structure has a first optical path from the first port waveguide to the second port waveguide, and a second optical path, different from the first optical path, from the first port waveguide to the second port waveguide. The first optical path has a portion, having a first length, within hydrogenated amorphous silicon. The second optical path has a portion, having a second length, within crystalline silicon, and the second optical path has either no portion within hydrogenated amorphous silicon, or a portion, having a third length, within hydrogenated amorphous silicon, the third length being less than the first length.

Provided is a variable wavelength filter having a wide variable wavelength range. In the variable wavelength filter, a slab waveguide that is a component of an arrayed-waveguide grating has a groove into which a resin is inserted. The groove intersects with a plurality of line segments A joining a place of connection between an input light waveguide and the slab waveguide to places of connection between respective array waveguides and the slab waveguide. The groove is formed such that a total length LA of an intersection of the groove and each of the line segments A monotonously increases or decreases between the adjacent line segments A with a difference in the total length LA between the adjacent line segments A being constant.

A broadband optical wavelength multiplexer/demultiplexer is provided. Two waveguides are arranged such that, in a case where a connection position where one of the two waveguides is connected to a first slab waveguide is set closer to the other waveguide by a channel frequency interval Δf, a central position between the two waveguides aligns with a central position on a connection end surface of the first slab waveguide, and two waveguide groups of an output waveguide are arranged such that a central position between the two waveguide groups aligns with a central position of a second slab waveguide, and an interval between a connection position where the other waveguide is connected to the first slab waveguide and the central position on the connection end surface of the first slab waveguide is set equal to an interval between a connection position where the waveguide groups are connected to the second slab waveguide.

The optical phased array may use a grating based emitter in order to emit light out of the plane of a PIC chip from an array of output waveguides. A longer grating allows for a larger aperture in the output waveguide dimension and allows for a small spot size. However, even for the relatively thick grating layers available in production foundries, the gratings still cause light to decay within less than 0.5 mm. To reduce the grating strength, some or all of the diffraction gratings may only be provided between the output waveguides, e.g. over trenches between the output waveguides, but not over top the output waveguides, whereby the periodicity only interacts with the weaker evanescent tails of the confined mode instead of the entire cross section of the output waveguides. By forming sufficiently narrow slots in the grating layer only down to the upper cladding layer, the diffraction gratings may be made extremely weak.

An optical array waveguide grating-type multiplexer and demultiplexer according to an embodiment of the present invention comprise: a first substrate, a plurality of first waveguides disposed on the first substrate to be superposed in the vertical direction, which is the thickness direction of the first substrate; a 1-1st cladding layer disposed between the first substrate and a 1-1st waveguide, which is nearest to the first substrate among the plurality of first waveguides; a 1-2nd cladding layer disposed between the plurality of first waveguides; and a 1-3rd cladding layer disposed on a 1-2nd waveguide, which is furthest from the first substrate among the plurality of first waveguides.

A multi-path interference filter. The multi-path interference filter includes a first port waveguide, a second port waveguide, and an optical structure connecting the first port waveguide and the second port waveguide. The optical structure has a first optical path from the first port waveguide to the second port waveguide, and a second optical path, different from the first optical path, from the first port waveguide to the second port waveguide. The first optical path has a portion, having a first length, within hydrogenated amorphous silicon. The second optical path has a portion, having a second length, within crystalline silicon, and the second optical path has either no portion within hydrogenated amorphous silicon, or a portion, having a third length, within hydrogenated amorphous silicon, the third length being less than the first length.

A dispersive optical phased array for two-dimensional scanning is disclosed herein. The array comprises antenna blocks positioned adjacent one another. The antenna blocks comprise a plurality of antennas positioned adjacent one another and a plurality of delay lines to couple a coherent source signal to each of the antennas within the block, each delay line having an optical path length. Each of the antenna blocks acts as a dispersive phased array. The antenna blocks are arranged such that the blocks form a larger phased array where the antennas between the blocks are in phase for a discrete set of wavelengths. All antennas over the dispersive phased array can experience the same phase difference such that the beams of the individual antenna blocks align with one of the diffraction orders of the array of blocks.

An arrayed waveguide grating. The arrayed waveguide grating includes two star couplers and an array of waveguides connecting the star couplers. The T-shaped geometry of the array of waveguides makes possible an AWG with an arbitrarily large free spectral range in a compact form factor. An array mode converter produces a field pattern, at an aperture of a free propagation region of a star coupler, having overlapping modes from adjacent waveguides.

A CMOS compatible heterogeneously integrated material platform for photonic integrated circuitry is invented. The material platform has SiO2 as cladding material, at least a bottom layer made of moderate refractive index (contrast) material(s), a bonded single crystal Si layer transfer from either a SOI wafer or a ion implanted single crystal Si wafer ready for ion cut split on top of the bottom layer, and some devices enabling light coupling between the devices made within these two layers. The invention provides a great material platform to offer a full set of photonic building blocks for all sorts of different applications such as photonic circuitry for optical neural network, quantum computing, telecommunication, data communication, optical switching, optical sensing, passive and/or active Si optical interposer with its size even bigger than lithography step field.

A CMOS compatible heterogeneously integrated material platform for photonic integrated circuitry is invented. The material platform has SiO2 as cladding material, at least a bottom layer made of moderate refractive index (contrast) material(s), a bonded single crystal Si layer transfer from either a SOI wafer or a ion implanted single crystal Si wafer ready for ion cut split on top of the bottom layer, and some devices enabling light coupling between the devices made within these two layers. The invention provides a great material platform to offer a full set of photonic building blocks for all sorts of different applications such as photonic circuitry for optical neural network, quantum computing, telecommunication, data communication, optical switching, optical sensing, passive and/or active Si optical interposer with its size even bigger than lithography step field.