Abstract: A first disclosure is an optical fiber member equipped with two holding members that hold an optical fiber such that an end surface of the optical fiber is located on one end and a curving portion having a coat of the optical fiber is curved to be extended at another end; the holding members are provided with holding flat portions that sandwich an end portion of the optical fiber where the coat is removed such that the end surface of the optical fiber is located on the one end; at least any of the holding flat portions has an aligning groove to fix a position of the end portion of the optical fiber; the holding member is provided with a curved surface at a position adjacent to the curving portion in the extending direction D1; and the two holding members are equal in thermal expansion coefficient.

Abstract: A first disclosure is an optical fiber member equipped with two holding members that hold an optical fiber such that an end surface of the optical fiber is located on one end and a curving portion having a coat of the optical fiber is curved to be extended at another end; the holding members are provided with holding flat portions that sandwich an end portion of the optical fiber where the coat is removed such that the end surface of the optical fiber is located on the one end; at least any of the holding flat portions has an aligning groove to fix a position of the end portion of the optical fiber; the holding member is provided with a curved surface at a position adjacent to the curving portion in the extending direction Dl; and the two holding members are equal in thermal expansion coefficient.

Abstract: A device that enables highly efficient optical coupling between an end face of an optical circuit and an optical fiber without using a V-groove substrate. An optical coupling device that includes an optical fiber, a high NA optical waveguide, a mode field conversion portion having a mode field diameter larger than that of an opposite end of the high NA optical waveguide, and a capillary having a through-hole for holding the high NA optical waveguide and the mode field conversion portion, wherein the opposite end of the high NA optical waveguide is placed in the end portion of the through-hole.

Abstract: An optical coupling device that exhibits high air tightness between a capillary and an optical fiber formed of the same glass material. An optical coupling device according to this disclosure includes: an optical fiber having an end portion being a bare fiber where a part of coating has been removed, metal plating being applied to the bare fiber around an end portion of the remaining coating and a circumference of the coating; a capillary having a through-hole having one end where the end portion of the bare fiber is positioned and the other end where the end portion of the coating of the optical fiber subjected to the metal plating is placed, metal plating being applied to an inner wall surface of the other end of the through-hole; and solder that seals a gap between the optical fiber 11 placed in the other end of the through-hole and an inner wall of the through-hole.

Abstract: A single-polarization single-mode optical fiber comprises a core made of silica glass, a clad surrounding the core and made of silica glass having a smaller index of refraction than the glass comprising the core, a pair of stress applying members symmetrically disposed on the clad and made of silica glass having different thermal expansion coefficient from that of the clad, spacers interposed between the stress applying members and made of silica glass having substantially the same thermal expansion coefficient as the clad, and a jacket surrounding the spacers, stress applying members. The jacket is also made of silica glass and has a smaller expansion coefficient than the stress applying members. The optical fiber of this invention has an excellent polarization preserving characteristic, low loss, long length, and stable characteristics.

Abstract: In a single mode optical fiber comprising a core made of glass and a cladding surrounding the core and made of glass, when a difference .DELTA. between refractive indices n.sub.1 and n.sub.2 of the core and cladding is expressed by (n.sub.1 -n.sub.2)/(n.sub.1).times.100%, the refractive indices n.sub.1 and n.sub.2 are determined to satisfy a relation 1.0<.DELTA.<3.6 and a diameter of the core is determined according to this value of .DELTA..

Abstract: In a single mode optical fiber of the type comprising a core, a cladding surrounding the core and an intermediate layer, the refractive indices n1, n2 and n3 respectively of the core, the cladding and the intermediate layer are selected such that the following relations are satisfied0.5<.DELTA.1<1.5-0.3>.DELTA.2>-1.