Nippon Telegraph and Telephone Public Corporation

Tetsuo Miya

Takao Edahiro

Katsunari Okamoto

Akio Kawana

Masao Kawachi

Yutaka Sasaki

Katusunari Okamoto

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.

Method for making single-polorization, single mode optical fibers

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&lt;.DELTA.&lt;3.6 and a diameter of the core is determined according to this value of .DELTA..

Single mode optical fibers

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 satisfied

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Mito, Japan

Tetsuo Miya