Two semiconductor chips are optically aligned to form a hybrid semiconductor device. Both chips have optical waveguides and alignment surface positioned at precisely-defined complementary vertical offsets from optical axes of the corresponding waveguides, so that the waveguides are vertically aligned when one of the chips is placed atop the other with their alignment surface abutting each other. The position of the at least one of the alignment surface in a layer stack of its chip is precisely defined by epitaxy. The chips are bonded at offset bonding pads with the alignment surfaces abutting in the absence of bonding material therebetween.

An integrated optical device, including: a semiconductor body delimited by a top surface; and at least one buried cavity, which extends in the semiconductor body, at a distance from the top surface, so as to delimit at the bottom a front semiconductor region, which functions as an optical guide.

The present disclosure describes methods of attaching surfaces together. In one aspect, a method includes depositing a first adhesive onto a first surface of a first item, the first adhesive forming a pattern that at least partially surrounds a region of the first surface where there is no first adhesive. A second adhesive is jetted onto the region of the first surface, wherein the second adhesive has a viscosity lower than a viscosity of the first adhesive. The first surface of the first item and a second surface of a second item are brought into contact with one another. The method also includes curing the first and second adhesives. While the methods can be particularly suitable for manufacturing optical light guide elements, the methods also can be used in other contexts and applications as well.

A method of fabricating a semiconductor device, the method comprising: forming a substrate; forming a support layer from a first type of material which is not susceptible to an etch process having a predetermined thickness that is related to a required thickness of the semiconductor device; forming a device on the support layer; forming at least one layer of cladding material on the device; forming a plurality of trenches in the layers that extend at least down to the substrate; applying a film over the cladding material; removing the substrate at least in part using an etching process to separate the device from others on a wafer.

Avalanche photodetector devices are disclosed in which spatial asymmetry is employed to preferentially enhance avalanche multiplication of electrons. In some example embodiments, an avalanche photodetector device includes p-doped and n-doped regions and a central waveguide region, where the p-doped region is laterally offset from the central waveguide by a first lateral offset region, and where the n-doped region is laterally offset from the central waveguide by a second lateral offset region. The first and second lateral offset regions are asymmetrically defined such that impact ionization and avalanche multiplication of electrons in the second laterally offset region is enhanced relative to that of holes in the first laterally offset region. In some example implementations, the asymmetry may be provided by a difference in relative heights and/or lateral spatial extends (widths) of the lateral offset regions, such that the electric field, or a spatial extent associated therewith, is enhanced for electrons.

Silicon carbide on insulator is provided by bonding bulk silicon carbide to a substrate with an oxide-oxide fusion bond, followed by thinning the bulk silicon carbide as needed. A doping-selective etch for silicon carbide is used to improve thickness uniformity of the silicon carbide layer(s).

An optical waveguide circuit includes: a ring waveguide; an input connection waveguide; an output connection waveguide; and an optical multiplexing/demultiplexing part that optically connects the ring waveguide with the input connection waveguide, and that optically connects the ring waveguide with the output connection waveguide. Further, at least one of the input connection waveguide and the output connection waveguide includes a plurality of curved waveguides, a sum total of products of curvature signs and bending angles of the curved waveguides and a sum total of a curvature sign and a bending angle of the ring waveguide have a same absolute value with signs opposite to each other, and rotation of a polarization plane of light generated in the ring waveguide and rotation of a polarization plane of light generated in the curved waveguides cancel each other out.

A core and a slab layer that are formed on a lower clad layer are provided. The lower clad layer is formed on a substrate. The core is comprised of a semiconductor and has a rectangular shape in a cross-sectional view. The slab layer is comprised of a semiconductor. The core and the slab layer have a thickness that allows only up to a secondary mode of light to be present. Further, the core and the slab layer are laminated on the lower clad layer. Further, the core and the slab layer are disposed to be optically coupled to each other.

A photonic integrated circuit chip includes vertical grating couplers defined in a first layer. Second insulating layers overlie the vertical grating coupler and an interconnection structure with metal levels is embedded in the second insulating layers. A cavity extends in depth through the second insulating layers all the way to an intermediate level between the couplers and the metal level closest to the couplers. The cavity has lateral dimensions such that the cavity is capable of receiving a block for holding an array of optical fibers intended to be optically coupled to the couplers.

A semiconductor optical device includes a substrate including a waveguide made of silicon and a semiconductor layer joined to the substrate so as to overlap the waveguide and including a diffraction grating formed of a first semiconductor layer and a second semiconductor layer having different refractive indices. The waveguide includes a bent portion and a plurality of straight portions that are connected to each other by the bent portion and that extend straight. The first semiconductor layer and the second semiconductor layer are each made of a compound semiconductor. The second semiconductor layer is embedded in the first semiconductor layer and includes a plurality of portions arranged in a direction in which the plurality of straight portions extend. The diffraction grating is positioned above the plurality of straight portions.