An optical waveguide device includes: a substrate having an electro-optic effect, an optical waveguide formed on the substrate, a light-receiving element disposed on the substrate and monitoring a light wave propagating through the optical waveguide or a light wave that is radiated from the optical waveguide; and a monitoring optical waveguide extending from the optical waveguide to the light-receiving element, in which the monitoring optical waveguide has a U-turn waveguide with respect to an output direction of the optical waveguide, and the light-receiving element is disposed at a part of the monitoring optical waveguide after the U-turn waveguide.

Apparatus for monitoring the output of an optical system. The apparatus comprises first and second fibre optic sections, a reflective coating, and a detector. The first fibre optic section has a first cladding and a first core, and is configured to receive light from the optical system at one end and has at the other end a first angled, polished face. The second fibre optic section has a second cladding and a second core, and has at one end a second angled, polished face. The first and second fibre optic sections are arranged such that the first and second angled, polished faces are substantially parallel and adjacent and the first and second cores are substantially aligned. The reflective coating is applied to the first or second angled, polished face, and is configured to reflect a portion of light transmitted through the first core. The detector is arranged to receive the reflected light.

An eye tracker comprises a light source; a detector; and first and second waveguides. The first waveguide comprises an input coupler for coupling source light into a waveguide path and a first grating for coupling light out of the waveguide path onto an eye. The second waveguide comprises a second grating for coupling light reflected from the eye into a waveguide path and an output coupler for coupling light out of the waveguide path onto the detector. The second grating is optically configured for imaging the eye onto the detector.

Glass-as-a-Platform (GaaP) assemblies are provided. Embodiments of the GaaP assembly comprise a first glass plate and a second glass plate, each disposed under one or more switch ASICs and one or more opto-electronic devices co-packaged on the same substrate. Each glass plate includes a plurality of waveguides. The co-packaged substrate is disposed on top of one or more of the first glass plate and second glass plate, the first glass plate configured to couple to one or more opto-electronic devices and the second glass plate configured to couple to one or more other opto-electronic devices. A faceplate interface end of each glass plate is configured to connect to one or more optical cable connectors. The glass plates are configured to route optical signals to and from one or more opto-electronic devices and one or more optical cable connectors through the one or more waveguides and openings in the co-packaged substrate.

Apparatus for monitoring the output of an optical system. The apparatus comprises first and second fibre optic sections, a reflective coating, and a detector. The first fibre optic section has a first cladding and a first core, and is configured to receive light from the optical system at one end and has at the other end a first angled, polished face. The second fibre optic section has a second cladding and a second core, and has at one end a second angled, polished face. The first and second fibre optic sections are arranged such that the first and second angled, polished faces are substantially parallel and adjacent and the first and second cores are substantially aligned. The reflective coating is applied to the first or second angled, polished face, and is configured to reflect a portion of light transmitted through the first core. The detector is arranged to receive the reflected light.

An optical waveguide device includes: a substrate having an electro-optic effect, an optical waveguide formed on the substrate, a light-receiving element disposed on the substrate and monitoring a light wave propagating through the optical waveguide or a light wave that is radiated from the optical waveguide; and a monitoring optical waveguide extending from the optical waveguide to the light-receiving element, in which the monitoring optical waveguide has a U-turn waveguide with respect to an output direction of the optical waveguide, and the light-receiving element is disposed at a part of the monitoring optical waveguide after the U-turn waveguide.

A light transmitting fibered medium comprises at least one optical fiber comprising a light output region comprising a light output window and a light guide region guiding a light wave to the light output region, and the light output window is formed in a spiral shape in an outer circumferential surface of the at least one optical fiber.

An eye tracker comprises a light source; a detector; and first and second waveguides. The first waveguide comprises an input coupler for coupling source light into a waveguide path and a first grating for coupling light out of the waveguide path onto an eye. The second waveguide comprises a second grating for coupling light reflected from the eye into a waveguide path and an output coupler for coupling light out of the waveguide path onto the detector. The second grating is optically configured for imaging the eye onto the detector.

A device may be provided comprising at least one optoelectronic component and at least one optical waveguide, which are configured to transfer light between the optoelectronic component and the optical waveguide, wherein the optical waveguide contains at least one first longitudinal portion in which at least one Bragg grating is introduced, which has a grating constant which is variable along the longitudinal extent of said Bragg grating, and the optoelectronic component is arranged at a lateral distance from the optical waveguide. Alternatively or in addition, a method may be provided for transferring light between at least one optoelectronic component and at least one optical waveguide.

A cladding mode stripper, includes: a resin part that covers a coating-removed section of an optical fiber and has a refractive index not less than that of an outermost shell of the optical fiber in the coating-removed section. A surface of the resin part includes an incident angle reducing structure. The surface is opposite to an interface between the resin part and the outermost shell. The incident angle reducing structure reduces a first incident angle or a first average incident angle at which cladding mode light that has entered the resin part from the optical fiber enters the surface.