In order to provides an optical waveguide element and an optical modulator that can prevent the damage to the substrate and the deterioration of the properties of the substrate that may occur due to the stress, by reducing the influence of stress on the substrate by the buffer layer, the optical waveguide 1 is provided with a substrate 5 having an electro-optical effect; an optical waveguide 10 formed on the substrate 5; a first buffer layer 9a provided on the substrate 5; and a second buffer layer 9b provided under the substrate 5, wherein the first buffer layer 9a and the second buffer layer 9b are composed of substantially the same material and have substantially the same thickness, and the first buffer layer 9a and the second buffer layer 9b are formed to be in contact with an upper surface and lower surface of the substrate 5, respectively.

Methods, systems, and devices are described for generating an optical signal. An example device may comprise a chip and a waveguide disposed on the chip and comprising silicon nitride. The waveguide may be configured to generate, based on nonlinear effects applied to a pump signal from a pump laser, an optical signal having a broader spectrum than the pump signal. The waveguide may have a width and a height such that the optical signal has near zero group-velocity-dispersion.

Electrical test of optical components via metal-insulator-semiconductor capacitor structures is provided via a plurality of optical devices including a first material embedded in a second material, wherein each optical device is associated with a different thickness range of a plurality of thickness ranges for the first material; a first capacitance measurement point including the first material embedded in the second material; and a second capacitance measurement point including a region from which the first material has been replaced with the second material.

An optical circuit element capable of preventing stray light propagated through a part including a substrate of the optical circuit element from being emitted to the outside is provided. The optical circuit element has a substrate, an optical waveguide layer that is formed on one surface of the substrate, and a protective layer that is overlaid on the optical waveguide layer. The optical waveguide layer has an optical waveguide configured for light to be propagated therethrough. A groove portion, which reaches to a position deeper than the one surface from a surface of the protective layer toward the substrate, is formed. The optical circuit element further includes a light absorption layer that covers at least a bottom surface and a side surface of the groove portion.

Structures for a cavity included in a photonics chip and methods of fabricating a structure for a cavity included in a photonics chip. The structure includes a substrate, a back-end-of-line stack having interlayer dielectric layers on the substrate, and a cavity penetrating through the back-end-of-line stack and into the substrate. The cavity includes first sidewalls and second sidewalls, and the second sidewalls have an alternating arrangement with the first sidewalls to define non-right-angle corners.

Provided is an optical phase shifter. The optical phase shifter includes: a slab waveguide in which a first slab region doped into a first conductivity type and a second slab region doped into a second conductivity type are arranged side by side to form a PN junction; and a rib waveguide disposed on the slab waveguide such that one side of the rib waveguide makes contact with the first slab region, and an opposite side of the rib waveguide makes contact with the second slab region, wherein the rib waveguide includes first to third rib waveguide layers that are sequentially stacked, the first and third rib waveguide layers include silicon (Si), and the second rib waveguide layer includes silicon-germanium (SiGe).

A photonic structure can include in one aspect one or more waveguides formed by patterning of waveguiding material adapted to propagate light energy. Such waveguiding material may include one or more of silicon (single-, poly-, or non-crystalline) and silicon nitride.

There is provided a method for fabricating a vertically tapered spot-size converter on a substrate, comprising: growing a waveguide core on the substrate; coating the waveguide core with a photoresist layer; placing a photomask having patterns at a negative focus offset point with respect to the photoresist layer, the patterns being defined by openings in the photomask, each opening having a cross-section comprising a region of constant width and at least one region of non-constant width, the non-constant width reducing in a direction extending away from the region of constant width; transferring the patterns of the photomask to the photoresist layer; providing the waveguide core with a vertically tapered profile, the vertically tapered profile being provided by the patterns of the photomask; growing a cladding layer over the waveguide core; and patterning and etching the cladding layer and the waveguide core, thereby defining the vertically tapered spot-size converter.

A method of fabricating a waveguide structure to form a solid-core waveguide from a waveguiding layer may include etching a fluid channel into the waveguiding layer, etching a first air-gap and a second air gap into the waveguiding layer, wherein etching the first and the second air-gaps creates a solid-core waveguide in the waveguiding layer between the first air-gap and the second air-gap. A method for fabricating a waveguide structure to form a solid-core waveguide may include forming a first trench, a second trench, and a third trench in a substrate layer, and depositing a waveguiding layer on the machined substrate layer, wherein depositing the waveguiding layer creates a hollow core of a fluid channel in a location corresponding to the first trench, and a solid-core waveguide portion in the waveguiding layer in a location corresponding to an area between the second trench and the third trench.

Embodiments may include or relate to an optical coupler. The optical coupler may include a silicon nitride (SiN) waveguide. The waveguide may be formed by placing SiN on an epitaxially grown silicon structure that is then removed subsequent to placement of the SiN. Other embodiments may be described and/or claimed.