Kokusai Denshin Denwa Kabushiki Kaisha

Kokusai Denshin Denwa Co., Ltd.

Japan Aviation Electronics Industry, Limited

Yoshinori Namihira

Kiyofumi Mochizuki

Hitoshi Yamamoto

Yoshihiro Yoshida

Hiroyuki Sasaki

Yukio Horiuchi

Hiroharu Wakabayashi

Yoshinao Iwamoto

Makoto Nunokawa

Masato Shimamura

A chromatic dispersion measuring method and apparatus are disclosed which permit highly accurate measurements of the wavelength dispersion characteristic of an optical transmission such as an optical fiber or an optical amplifier repeater system. Measurements are made on the propagation time of a first optical signal of a fixed wavelength through an optical transmission line to be measured and the propagation time through the same optical transmission line of a second optical signal whose wavelength can be arbitrarily set over the measuring wavelength band. By obtaining a difference between the both propagation times, it is possible to obtain only a change in the propagation time of each signal which is caused by a change in the wavelength of the second optical signal. That is, the elongation or shrinkage of the optical fiber has an equal influence on both of the first optical signal and the second optical signal, and hence does not induce an error in the detection of the above-said time difference.

Method and apparatus for chromatic dispersion measurements

In an optical fiber coupler there is provided, in an optical coupling portion between cores of two partly fused together and extended optical fiber, an optical coupling control portion which has a refractive index different from those of claddings covering the cores.

Optical fiber coupler and its manufacturing Method

An optical fiber cable in which at least those metallic members of the optical fiber cable which are of high chemical reactivity and electrochemical reactivity are each precoated with a film for preventing them from making direct contact with water when it diffuses into the cable. The film may be a nonmetallic film or a metallic film of low chemical reactivity and electrochemical reactivity.

Optical fiber cable

An optical de-polarizer is implemented by using an optical fiber, and/or a beam splitter coupled with output of said optical fiber. An optical fiber is longer than a predetermined length so that equation .vertline.t.sub.1 -t.sub.2 .vertline.&gt;t.sub.c is satified where t.sub.1 is polarization mode dispersion in a first optical fiber, t.sub.2 is a polarization mode dispersion in a second optical fiber which is coupled with output of the first optical fiber, and t.sub.c is coherence time of a beam defined by an optical source. According to the present invention, one of the conditions (1) an angle between polarization axis of the first optical fiber and polarization axis of the second optical fiber is 45.degree., and (2) an angle between polarization axis of the optical fiber and polarization axis of the beam splitter is 45.degree., is satisfied.

Optical de-polarizer

Growing community of inventors

Hachioji, Japan

Yoshinori Namihira