A process for polishing the end face of a plastic optical fiber (POF) to produce a mirror smooth surface without any defect. Smooth POF end faces reduce the optical coupling loss when two plastic optical fibers are connected. The polishing process can be used to produce POF end faces which are recessed relative to the adjacent end face of a ferrule surrounding the fiber. When the ends of two ferrules are inserted in a connector designed to align the end faces of the ferrules while allowing those end faces to abut each other, the confronting recessed POF end faces will be separated by an air gap.

An optical receptacle includes: a fiber stub including an optical fiber, a ferrule, and an elastic member; and a holder holding the fiber stub, the optical fiber including a cladding and a core for conducting light, the ferrule having a through-hole fixing the optical fiber, the elastic member fixing the optical fiber in the through-hole, the fiber stub having one end surface on the ferrule side, and another on an opposite side, the optical fiber including first and third portions on the opposite end surface sides and a second portion therebetween, a core diameter of the first portion being smaller than the third portion, and a core diameter of the second portion increasing from the first portion side toward the third portion side.

Waveguide connectors include a ferrule having first alignment features. A polymer waveguide has one or more a topclad portions, each with a waveguide core, second alignment features fastened to the first alignment features, and underclad portion that is thicker than the one or more topclad portions. The polymer waveguide has a higher coefficient of thermal expansion than the ferrule and is fastened to the ferrule under tension.

Methods for providing flammability protection for plastic optical fiber (POF) embedded inside avionics line replaceable units (LRUs) or other equipment used in airborne vehicles such as commercial or fighter aircrafts. A thin and flexible flammability protection tube is placed around the POF. In one proposed implementation, a very thin (100 to 250 microns in wall thickness) polyimide tube is placed outside and around the POF cable embedded inside an LRU or other equipment. The thin-walled polyimide tube does not diminish the flexibility of the POF cable.

A feeding tube position confirmation device 102, operable to confirm the position of a predetermined portion of a medical feeding tube in a predetermined portion of a human or animal body, the position confirmation device comprising an optical waveguide 106 dimensioned to be insertable into the lumen of the feeding tube, the optical waveguide having a sensing distal end 108 comprising a distal end material and a sensing material mixed with the distal end material, the sensing material operable to provide a change in optical properties at the distal end 110 of the optical waveguide dependent on the environment to which the sensing distal end 108 of the waveguide is exposed. The sensing material may comprise a reflective material. Methods of manufacture and use of such devices are also described.

The present technology provides an illustrative method for preparing fibers with desirable optical characteristics. The method includes providing a fiber that comprises a core layer and a cladding layer located around the core layer. The method further includes applying a nanostructure template to the cladding layer to form one or more photonic nanostructures having nanostructure scales and compressing the core layer to cause the core layer to bulge and form air gaps between the core layer and the one or more photonic nanostructures.

A thermoplastic filament comprising multiple polymers of differing flow temperatures in a geometric arrangement is described. A method for producing such a filament is also described. Because of the difference in flow temperatures, there exists a temperature range at which one polymer is mechanically stable while the other is flowable. This property is extremely useful for creating thermoplastic monofilament feedstock for three-dimensionally printed parts, wherein the mechanically stable polymer enables geometric stability while the flowable polymer can fill gaps and provide strong bonding and homogenization between deposited material lines and layers. These multimaterial filaments can be produced via thermal drawing from a thermoplastic preform, which itself can be three-dimensionally printed. Furthermore, the preform can be printed with precisely controlled and complex geometries, enabling the creation of a filament or fiber with a wide range of applications. A method is also described for including an interior thread that adds structural reinforcement or functional properties, such as electrical conductivity or optical waveguiding, to the filament.

A plastic optical fiber for a medical device lighting decreases the cost of a lens and simplify the design of a lighting apparatus, wherein the plastic optical fiber for a medical device includes a core composed of a (co)polymer containing methyl methacrylate as a main component and is characterized by including a cladding material composed of a copolymer having a fluorine weight composition ratio of 60 to 74%, and by having a theoretical numerical aperture, NA, of 0.48 to 0.65 and, thus, the plastic optical fiber has a high numerical aperture and also has excellent translucency and flexibility.

The fluorine-containing copolymer of the present invention includes: a structural unit (A) represented by the following formula (1); and at least one selected from the group consisting of a structural unit (B) represented by the following formula (2), a structural unit (C) represented by the following formula (3), and a structural unit (D) represented by the following formula (4):

##STR00001##

in the formula (1), R.sub.ff.sup.1 to R.sub.ff.sup.4 each independently represent a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms, and R.sub.ff.sup.1 and R.sub.ff.sup.2 are optionally linked to form a ring;

##STR00002##

in the formula (2), R.sup.1 to R.sup.3 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, R.sup.4 represents a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are optionally substituted by a halogen atom other than a fluorine atom, and one or some of fluorine atoms in the perfluoroalkyl group are optionally substituted by a halogen atom other than a fluorine atom;

##STR00003##

in the formula (3), R.sup.5 to R.sup.8 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are optionally substituted by a halogen atom other than a fluorine atom, and one or some of fluorine atoms in the perfluoroalkyl group are optionally substituted by a halogen atom other than a fluorine atom; and

##STR00004##

in the formula (4), Z represents an oxygen atom, a single bond, or —OC(R.sup.19R.sup.20)O—, R.sup.9 to R.sup.20 each independently represent a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms, one or some of the fluorine atoms are optionally substituted by a halogen atom other than a fluorine atom, one or some of fluorine atoms in the perfluoroalkyl group are optionally substituted by a halogen atom other than a fluorine atom, one or some of fluorine atoms in the perfluoroalkoxy group are optionally substituted by a halogen atom other than a fluorine atom, s and t are each independently 0 to 5, and s+t represents an integer of 1 to 6 (when Z is —OC(R.sup.19R.sup.20)O—, s+t is optionally 0).

An optical fiber is a linear radiator uniform in the longer direction thereof, and a lighting device uses the optical fiber. The optical fiber is a lighting fiber having a core and a cladding. In the fiber, as the cladding, there is used a polymer obtained by polymerizing a polymerizing ingredient containing 90% or more by weight of vinylidene fluoride, and the cladding has a crystallinity of 45% to 52%.