Nippon Telegraph and Telephone Corporation

Mitsubishi Cable Industries, Ltd.

Kazunori Suzuki

Satoki Kawanishi

Masatoshi Tanaka

Moriyuki Fujita

Hirokazu Kubota

A 1.55 &#x3bc;m band dispersion shifted optical fiber is provided which has a low loss and low dispersion slope. A core region 'a' is heavily doped with GeO. A core region 'b' is composed of pure SiOglass. A cladding section is arranged around the core region. The cladding section has a lot of holes extending in the longitudinal direction of the optical fiber. The holes of the cladding section are not located at random, but have a honeycomb structure composed of regular hexagons which have a side length of &#x39b;, and serve as a primitive lattice. The center of the core section has a region having a refractive index higher than that of the periphery of the core section. The core section has the refractive index distribution in which the group velocity dispersion at the operation wavelength of the region becomes the normal dispersion.

Dispersion shifted optical fiber

A polarization-maintaining optical fiber and absolutely single-polarization optical fiber are provided which enable long distance transmission maintaining a polarization state of signal light. The polarization-maintaining optical fiber includes a core, photonic crystal cladding, and jacket. The photonic crystal cladding is divided into four segments by broken lines from the center to the periphery. Among a plurality of grating holes in a pair of segments opposed to each other with respect to the core, the diameter of grating holes close to the core is greater than the diameter of grating holes in another pair of segments opposed with each other, and than a grating constant.

Growing community of inventors

Yokosuka, Japan

Kazunori Suzuki