A co-doped optical fiber is provided having an attenuation of less than about 0.17 dB/km at a wavelength of 1550 nm. The fiber includes a core region in the fiber having a graded refractive index profile with an alpha of greater than 5. The fiber also includes a first cladding region in the fiber that surrounds the core region. Further, the core region has a relative refractive index of about −0.10% to about +0.05% compared to pure silica. In addition, the core region includes silica that is co-doped with chlorine at about 1.2% or greater by weight and fluorine between about 0.1% and about 1% by weight.

A temperature sensor and temperature sensing system for sensing changes m temperature up to a predetermined temperature is disclosed. The temperature sensor includes a microstructured optical fiber where the micro-structured optical fiber includes a plurality of longitudinal channels extending along the microstructured optical fiber. The sensor also includes a fiber Bragg grating formed in the microstructured optical, fiber by generating a periodic modulation in the refractive index along a core region of the microstructured optical fiber. The fiber Bragg grating is operable to produce band reflection at a reflection wavelength that varies in accordance with changes in temperature at the core region of the optical fiber.

An optical element is configured to transmit a light flux emitted from a light source having a single light source wavelength, and is formed from a material in which resin and glass fillers are mixed. A difference between respective refractive index change rates (dn/dT) of the resin and the glass fillers relative to a temperature change at least in a vicinity of the light source wavelength becomes 10.5×10.sup.5 or less.

There is provided a method for making an optical element having a textured surface. The method comprises the steps of: a) providing a plurality of primary optical fiber segments, each primary fiber segment comprising one or more cores; b) bundling the primary fiber segments into an assembly with the cores of said primary fiber segments extending parallely; c) transforming the assembly into a secondary structure comprising the parallely extending cores; and d) etching a surface of the secondary structure according to an etch profile of said secondary structure, the etch profile being defined by the parallely extending cores, thereby forming the textured surface of the optical element. An optical element having a textured surface is also provided.

The low magnetic sensitivity PM-PCF based on mechanical buffer is obtained by adding buffer structures in the cladding layer of the photonic crystal fiber. In the center of the fiber, the core region contains at least 3 layers of air-holes, enclosed by the cladding layer. The buffer structures are placed in the cladding layer. These buffer structures are formed by replacing silica of any shape by air, and are symmetrically located in X-axis and Y-axis directions to achieve mechanical isotropy. The buffer structures improve the fiber's performance in fiber coiling and stress conditions. Therefore, the fiber optic gyroscope using the PM-PCF can do without a magnetic shield, thus greatly reducing the weight of the fiber optic gyroscope and extending the scope of its application. Compared with the conventional commercial PCF, the PM-PCF provides the fiber optic gyroscope with lower temperature sensitivity and improved accuracy.

A multi-purpose sealing device is described herein for use in a port structure of fiber terminal, telecommunication enclosure; or a bulkhead. The exemplary sealing device has a body having an open end and a closed end, wherein the closed end includes a removable portion and a pulling device to facilitate removal of the exemplary sealing device from a port structure. In one aspect, the exemplary sealing device is a single part made of a resilient material, while an alternative aspect, the exemplary sealing device includes a rigid connection portion disposed within the open end of the body. The exemplary device can be used as a dust cap or plug prior to making a service connection and/or it can be used as a port/cable sealing device after the service connection is made.

A multi-purpose optical fiber with coating is provided. The optical fiber can function as a transmission fiber or as a coupling fiber for optical data links that features low coupling loss to silicon photonics lasers, VCSELs, single mode transmission fibers, multimode transmission fibers, and high speed receivers. The fiber includes a core, an optional inner cladding region, a depressed index cladding region, an outer cladding region, and a coating. The relative refractive index profile of the coupling fiber includes a small-radius core region with α profile and a depressed index cladding region that facilitates low bending loss and high bandwidth. The coating thickness and overall diameter of the fiber is small.

Optical waveguide cores having refractive index profiles that vary angularly about a propagation axis of the core can provide single-mode operation with larger core diameters than conventional waveguides. In one representative embodiment, an optical waveguide comprises a core that extends along a propagation axis and has a refractive index profile that varies angularly about the propagation axis. The optical waveguide can also comprise a cladding disposed about the core and extending along the propagation axis. The refractive index profile of the core can vary angularly along a length of the propagation axis.

Optical waveguide cores having refractive index profiles that vary angularly about a propagation axis of the core can provide single-mode operation with larger core diameters than conventional waveguides. In one representative embodiment, an optical waveguide comprises a core that extends along a propagation axis and has a refractive index profile that varies angularly about the propagation axis. The optical waveguide can also comprise a cladding disposed about the core and extending along the propagation axis. The refractive index profile of the core can vary angularly along a length of the propagation axis.

Polymeric compositions comprising a blend of high-density polyethylene (“HDPE”) with ethylene vinyl acetate (“EVA”), and optionally with a carbon black and/or one or more other additives, where the polymeric compositions have certain melt-index and vinyl-acetate-content ranges to improve melt strength and processability. Such polymeric compositions can be employed in manufacturing coated conductors, such as fiber optic cables.