Embodiments of an optical adhesive are provided. The optical adhesive includes about 20% to about 60% by volume of first monomers. The first monomers have at least two acrylate or methacrylate groups. The optical adhesive also includes about 40% to about 80% by volume of second monomers. The second monomers have at least one fluorine atom and at least one acrylate or methacrylate group. The optical adhesive has a refractive index of from about 1.40 to about 1.55, and in the temperature range of about 10 C. to about 85 C., the refractive index of the optical adhesive has a thermal drift dn/dT of less than about 410.sup.4/ C. Embodiments of a mechanical joint between two optical fiber segments using the optical adhesive and embodiments of a method for joining two optical fiber segments are also provided.

A dual-core waveguide architecture provides two evanescently coupled waveguides where a first waveguide is doped with an active gain species to produce optical power and a second waveguide that runs parallel to the first waveguide is configured to collect the power produced by the first waveguide. Power is harvested from the second waveguide.

An optical transmission system according to the present disclosure is a mode multiplexed optical transmission system using a multi-mode optical fiber in which a plurality of propagation modes propagate as a transmission line, the optical transmission system including an optical fiber transmission line (83) that includes an optical fiber with two or more propagation modes; and a plurality of mode converters (91) that are configured to generate mode coupling between at least one pair of the propagation modes, in which a variation in an installation interval of the plurality of mode converters (91) is equal to or less than a threshold value determined by the transmission line length (Lt) of the optical fiber transmission line (83).

Disclosed herein is an optical fiber having an optically uniform coating having no physical defects in the coating greater than 100 micrometers in size over a length of 50 meters or greater.

Disclosed are grating couplers having a high coupling efficiency for optical communications. In one embodiment, an apparatus for optical coupling is disclosed. The apparatus includes: a substrate; a grating coupler comprising a plurality of coupling gratings over the substrate, wherein each of the plurality of coupling gratings extends in a first lateral direction and has a cross-section having a middle-raised shape in a second lateral direction, wherein the first and second lateral directions are parallel to a surface of the substrate and perpendicular to each other in a grating plane; and a cladding layer comprising an optical medium, wherein the cladding layer is filled in over the grating coupler.

Embodiments of an optical adhesive are provided. The optical adhesive includes about 20% to about 60% by volume of first monomers. The first monomers have at least two acrylate or methacrylate groups. The optical adhesive also includes about 40% to about 80% by volume of second monomers. The second monomers have at least one fluorine atom and at least one acrylate or methacrylate group. The optical adhesive has a refractive index of from about 1.40 to about 1.55, and in the temperature range of about 10 C. to about 85 C., the refractive index of the optical adhesive has a thermal drift do/dT of less than about 410.sup.4/ C. Embodiments of a mechanical joint between two optical fiber segments using the optical adhesive and embodiments of a method for joining two optical fiber segements are also provided.

Systems and methods of dispersion compensation in an optical device are disclosed. A holographic optical element may include a set of different holograms in a grating medium. Each hologram in the set may have a corresponding grating vector with a grating frequency and direction. The directions of the grating vectors may vary as a function of the grating frequency. Different holograms in the set may diffract light in a particular direction so that the light emerges from a boundary of the grating medium in a single given direction regardless of wavelength. A prism may be used to couple light into the grating medium. The prism may be formed using materials having dispersion properties that are similar to the dispersion properties of the grating material. The prism may have an input face that receives perpendicular input light. The prism may include multiple portions having different refractive indices.

Systems and methods of dispersion compensation in an optical device are disclosed. A holographic optical element may include a set of different holograms in a grating medium (704). Each hologram in the set may have a corresponding grating vector (708, 710, 712) with a grating frequency and direction. The directions of the grating vectors may vary as a function of the grating frequency. Different holograms in the set may diffract light in a particular direction so that the light emerges from a boundary of the grating medium in a single given direction regardless of wavelength. A prism (722) is used to couple light into the grating medium. The prism is formed using materials having dispersion properties that are similar to the dispersion properties of the grating material but not indentical. The prism may have an input face that receives perpendicular input light. The prism may include multiple portions having different refractive indices.

Strands of material may be intertwined to form fabric for a strap or other structure in an electronic device. Conductive strands in the fabric may have middle-of-strand knots. When current is applied to a conductive strand, the knot in that strand may produce magnetic fields that cause the knot to adjust tension in the fabric. Conductive strands may intersect at nodes. Each node may have a knot formed from one or more conductive strands at the node. An electronic device or other item may have a magnetic field source that applies a fixed or time-varying magnetic field to the fabric. Each node in the fabric may include magnetic material. The magnetic material may be magnetized by applying current through the conductive strands. After magnetization, each node may interact with the magnetic field from the source of magnetic field to thereby adjust fabric tension, shape, movement, etc.

Systems and methods of dispersion compensation in an optical device are disclosed. A holographic optical element may include a set of different holograms in a grating medium (704). Each hologram in the set may have a corresponding grating vector (708, 710, 712) with a grating frequency and direction. The directions of the grating vectors may vary as a function of the grating frequency. Different holograms in the set may diffract light in a particular direction so that the light emerges from a boundary of the grating medium in a single given direction regardless of wavelength. A prism (722) is used to couple light into the grating medium. The prism is formed using materials having dispersion properties that are similar to the dispersion properties of the grating material but not indentical. The prism may have an input face that receives perpendicular input light. The prism may include multiple portions having different refractive indices.