A light-emitting module includes a substrate, a surface light-emitting element, and an optical waveguide. The surface light-emitting element includes light sources and is attached to the substrate. The optical waveguide is attached to the surface light-emitting element in a state in which the optical waveguide covers the light sources. The optical waveguide extends in an axial direction with a refractive index distribution in a radial direction. The optical waveguide condenses light beams emitted from the surface light-emitting element.

An integrally molded multi-optical transmission sheet includes: a sheet-like coated portion formed of plastic; and a plurality of optical transmission regions having a core region formed of plastic, and a clad region formed of plastic and surrounding an outer periphery of the core region, which are provided inside the coated portion to extend along an extending direction of the coated portion, wherein the plurality of optical transmission regions are arranged in a row substantially parallel to each other along a main surface of the coated portion, and in a case where light is incident from one end face side of the plurality of optical transmission regions and transmitted toward the other end face side, a M.sup.2 value of emitted light is 1.7 or more.

A polarization-independent orbital angular momentum modulator based on a chiral fiber grating, a method for manufacturing the same, and an orbital angular momentum beam generator. The orbital angular momentum modulator includes an optical fiber body having a spiral fiber structure, and the spiral fiber structure has a long-period optical fiber grating effect. The optical fiber body has a periodic spiral refractive index modulation in an axial direction. A period of the spiral refractive index modulation has a magnitude of hundreds of microns, and the spiral refractive index modulation is distributed in an axial direction, a radial direction, and an angular direction of the optical fiber body, and configured to excite a spiral phase to generate an orbital angular momentum beam.

A substrate can include an optical light guide including a core. The core can include a fluorescent material in a content of greater than 0.5 wt. % for the total weight of the core. In an embodiment, the optical light guide can include a scintillator material. In another embodiment the core can include polyethylene naphthalate (PEN) and a polyvinylidene difluoride cladding.

An optical element includes a waveguide body that is configured to guide light by total internal reflection from an input end to an output end, an input coupling structure located at the input end for coupling light into the waveguide body, and an output coupling structure located at the output end for coupling light out of the waveguide body, where the waveguide body includes a layer of an optically anisotropic organic solid crystal. Such an optical element may have low weight and exhibit good color uniformity while presenting a 2D diagonal field-of-view of at least approximately 10°.

An optical fiber is formed from silica glass, and includes a core, a first cladding which surrounds the core and has a refractive index lower than the refractive index of the core, and a second cladding which surrounds the first cladding and has a refractive index that is lower than the refractive index of the core and higher than the refractive index of the first cladding. The second cladding is divided into an inner region that is in contact with the first cladding and an outer region which surrounds the inner region and has a thickness that is half the thickness of the second cladding or less, while being 5 μm or more. The residual stress in at least a part of the outer region is a compressive stress.

Provided is an optical fiber cable which allows for high-quality signal transmission in short-distance transmission. The optical fiber cable is designed for use in optical communication based on transmitting an optical beam from a light-emitting device, to a light-receiving device. The optical fiber cable has: a proximal end which is one end thereof on the side of the light-emitting device, and a distal end which is the other end thereof on the side of the light-receiving device, wherein an optical beam returning from the side of the distal end toward the side of the light-emitting device has an M.sup.2 factor of 1.7 or more; and a length of 50 m or less.

A process for polishing the end face of a gigabit plastic optical fiber (GbPOF) to produce a mirror smooth surface without any defect. Smooth GbPOF end faces reduce the optical coupling loss when two plastic optical fibers are connected. The polishing process can be used to produce GbPOF end faces which are free of defects such as scratches. The polishing process involves the use of successive abrasive films having decreasing surface roughness to abrade the end of a GbPOF. More specifically, each subsequently applied abrasive film has a mean particle size which is less than the mean particle size of the previously applied abrasive film.

An optical fiber is provided that includes a core region and a cladding region. The core region is formed of silica glass doped with chlorine and/or an alkali metal. The cladding region surrounds the core region and includes an inner cladding directly adjacent to the core region, an outer cladding surrounding the inner cladding, and a trench region disposed between the inner cladding and the outer cladding in a radial direction. The trench region has a volume of about 30% Δ-micron.sup.2 or greater. Additionally, the optical fiber has an effective area at 1550 nm of about 100 micron.sup.2 or less.

An integrally molded multi-optical transmission sheet includes: a sheet-like coated portion formed of plastic; and a plurality of optical transmission regions having a core region formed of plastic, and a clad region formed of plastic and surrounding an outer periphery of the core region, which are provided inside the coated portion to extend along an extending direction of the coated portion, wherein the plurality of optical transmission regions are arranged in a row substantially parallel to each other along a main surface of the coated portion, and in a case where light is incident from one end face side of the plurality of optical transmission regions and transmitted toward the other end face side, a M.sup.2 value of emitted light is 1.7 or more.