The present disclosure relates to polarization rotator-splitters that include oxide claddings. One example embodiment includes a device. The device includes a first waveguide. The first waveguide includes a first end configured to receive electromagnetic waves having a first polarization with a first mode-order and electromagnetic waves having a second polarization. The first waveguide also includes a mode-conversion section configured to convert electromagnetic waves having the second polarization into electromagnetic waves having the first polarization with a second mode-order. Additionally, the device includes a second waveguide. The second waveguide also includes a coupling section configured such that electromagnetic waves having the first polarization with the second mode-order are converted into electromagnetic waves having the first polarization with the first mode-order and coupled from the coupling section of the first waveguide into the coupling section of the second waveguide.

Structures for an optical power splitter and methods of forming a structure for an optical power splitter. A first waveguide core includes a portion positioned over a multimode interference region, a second waveguide core includes a portion positioned over the multimode interference region, and a third waveguide core includes a portion positioned over the multimode interference region. The first waveguide core provides an input port to the optical power splitter. The second waveguide core provides a first output port from the optical power splitter, and the third waveguide core provides a second output port from the optical power splitter.

A method of manufacturing a semiconductor optical device includes a step of bonding a semiconductor element to a substrate that includes silicon, the semiconductor element being made of a III-V compound semiconductor and having optical gain; after the step of bonding the semiconductor element, a step of molding the semiconductor element by wet-etching; and after the step of molding the semiconductor element, a step of forming a mesa at the semiconductor element. The substrate includes a waveguide, a groove that extends along the waveguide, a terrace that is positioned on a side of the groove opposite to the waveguide, and a wall that covers the groove. The step of bonding the semiconductor element is a step of bonding the semiconductor element to the waveguide, the groove, the terrace, and the wall of the substrate.

The present disclosure provides a light detecting device. The light detecting devices includes an insulating layer, a silicon layer, a light detecting layer, N first doped regions and M second doped regions. The silicon layer is disposed over the insulating layer. The light detecting layer is disposed over the silicon layer and extends within at least a portion of the silicon layer. The first doped regions have a first dopant type and are disposed within the light detecting layer. The second doped regions have a second dopant type and are disposed within the light detecting layer. The first doped regions and the second doped regions are alternatingly arranged. M and N are integers equal to or greater than 2.

Disclosed are apparatus and methods for optical coupling in optical communications. In one embodiment, an apparatus for optical coupling is disclosed. The apparatus includes: a planar layer; an array of scattering elements arranged in the planar layer at a plurality of intersections of a first set of concentric elliptical curves crossing with a second set of concentric elliptical curves rotated proximately 90 degrees to form a two-dimensional (2D) grating; a first taper structure formed in the planar layer connecting a first convex side of the 2D grating to a first waveguide; and a second taper structure formed in the planar layer connecting a second convex side of the 2D grating to a second waveguide. Each scattering element is a pillar into the planar layer. The pillar has a top surface whose shape is a concave polygon having at least 6 corners.

The present disclosure relates to semiconductor structures and, more particularly, to multi-mode optical waveguide structures with isolated absorbers and methods of manufacture. The structure includes: a waveguide structure including tapered segments; and at least one isolated waveguide absorber adjacent to the waveguide structure along its length.

Integrated passive/active modulator units, integrated passive/active modulators comprising one or more units, and corresponding methods of fabrication and use are provided. In an example embodiment, a unit comprises an upstream passive portion comprising a passive waveguide; a downstream passive portion comprising a continuation of the passive waveguide; and an active portion between the upstream passive portion and the downstream passive portion. The active portion comprises an active waveguide and electrical contacts in electrical communication with the active waveguide. The active waveguide comprises an upstream taper and/or a downstream taper. The upstream taper is configured to optically couple the active waveguide to the passive waveguide of the upstream portion and the downstream taper is configured to optically couple the active waveguide to the continuation of the passive waveguide of the downstream portion.

A large-area, waveguide-based, high-speed ultraviolet and visible light photodetector system for optical wireless communication includes a substrate; plural, parallel, waveguides formed directly on the substrate and including a high quantum-yield wavelength-converting material of semiconductor nature; an optical coupling system optically connected to each one of the plural, parallel, waveguides; and a photodetector optically connected to the optical coupling system and configured to detect an outgoing light. The wavelength-converting material converts a first wavelength of an incoming light at high-speed, received by the plural, parallel, waveguides, into a second wavelength of the outgoing light. The first wavelength is different from the second wavelength, and the first and second wavelengths are between 200 and 800 nm.

Structures for a photodetector and methods of fabricating a structure for a photodetector. A photodetector includes a photodetector pad coupled to a waveguide core and a light-absorbing layer coupled to the photodetector pad. The light-absorbing layer has a body, a first taper that projects laterally from the body toward the waveguide core, and a second taper that projects laterally from the body toward the waveguide core. The photodetector pad includes a tapered section that is laterally positioned between the first taper and the second taper of the light-absorbing layer.

A 90-degree optical hybrid includes two optical splitters that respectively split inputted light into two beams, two optical combiners that respectively combine two beams of inputted light and thereby output two beams of interfering light respectively, and four arm waveguides that input light splitted by any of the two optical splitters into any of the two optical combiners. Each of the four arm waveguides has a bend waveguide arranged at its center and a plurality of optical waveguides including a tapered waveguide having a width that decreases toward the bend waveguide. Both ends of each of the plurality of optical waveguides are respectively in contact with a end surface of any one of the two optical splitter, the two optical combiners, the bend waveguide and the other of the plurality of optical waveguides, and each of the plurality of waveguides is the tapered waveguide or a linear waveguide.