Sumitomo Electric Industries, Limited

J-power Systems Corporation

Fumiyoshi Ohkubo

Takatoshi Kato

Yoshiaki Terasawa

Yosuke Yamazaki

Toshiaki Okuno

Masato Tanaka

Yasushi Koyano

Kazuaki Negishi

Hidehiko Komeda

Tsuyoshi Igi

An optical fiber temperature distribution measuring apparatus and a method for measuring optical fiber temperature distribution, provided with a light source for inputting a pulse light to an optical fiber to be measured, a signal detecting unit for detecting a received light intensity of a predetermined light included in a backscattering light generated by an input of the pulse light in the optical fiber to be measured, and a signal processing unit for calculating a value corresponding to a variation of the received light intensity due to a hydrogen molecular absorption of the optical fiber to be measured based on the received light intensity of the predetermined light, to compensate the received light intensity of the predetermined light corresponding to a temperature of the optical fiber to be measured based on the value.

Optical fiber temperature distribution measuring apparatus, method for measuring optical fiber temperature distribution, and optical fiber temperature distribution measuring system

It is an object of the present invention to provide an optical transmission system in which multiple optical frequencies can be efficiently used and the change of the system can be easily made, and to provide an optical demultiplexer suitable for such optical transmission system. In an optical demultiplexer according to the present invention, signal light having a plurality of wavelength components arranged on a grid having predetermined frequency intervals is input from an input port thereof to be demultiplexed. The demultiplexed signal lights output from the output ports thereof have a plurality of wavelength components, respectively, and any three wavelength components, f, f, and f, that satisfy the following conditions: f&#x3c;f&#x3c;f; and f&#x2212;f&#x2266;N&#x394;f have the following relationship: 2f&#x2260;f+fwhere N represents an integer, and &#x394;f represents each of the predetermined frequency intervals.

Optical demultiplexer and optical transmission system

This invention relates to a single-mode optical fiber having a configuration for effectively reducing bending loss. In the single-mode optical fiber, while an optical core is constituted by inner and outer cores, an optical cladding is constituted by an inner cladding in which 'tailing' occurs and an outer cladding. In particular, in a cross section of the optical fiber perpendicular to the signal light guiding direction, when the surface integral values of relative refractive index difference of the optical cladding and optical core with respect to the outer cladding having an average refractive index n.sub.0 are respectively S1 and S2, the optical fiber satisfies a relationship of S1/S2.gtoreq.0.8.

Single-mode optical fiber

The present invention relates to an S-mode optical fiber having a structure which can effectively restrain dispersion slope from increasing. In this S-mode optical fiber, an optical core is constituted by inner and outer cores, while an optical cladding is constituted by an inner cladding in which 'tailing' occurs and an outer cladding. In a cross section of the S-mode optical fiber perpendicular to its signal light propagating direction, when surface integral values of relative refractive index difference with respect to a reference region having an average refractive index n.sub.0 are S1 and S2 in the optical cladding and optical core, respectively, the S-mode optical fiber is designed to satisfy a relationship of 0&lt;S1/S2.ltoreq.0.3. As a result of this configuration, it can effectively restrain dispersion slope from increasing due to 'tailing' which inevitably occurs during its manufacturing process.

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Kanagawa, Japan

Fumiyoshi Ohkubo