Fujitsu Corporation

Tokyo Gas Company Limited

Seiichi Ikeda

Nobuhiro Fukushima

Hiroaki Kobayashi

Shigeru Toyoda

Seimi Sasaki

Hirohiko Sonoda

Minoru Imamura

Hirohiko Sonada

An optical integrated device in which application of an excessive stress or the appearance of a crack due to thermal expansion mismatching is prevented. A first ferrule is fixed to an optical waveguide chip. An optical fiber is inserted into the first ferrule to fix the optical fiber. A package contains the optical waveguide chip and the first ferrule. An opening is made in a sidewall of the package to pull out the optical fiber to the outside. A pipe is airtightly fixed around the opening. A second ferrule is inserted into the pipe and is airtightly fixed to an end of the pipe. The optical fiber pulled out to the outside of the package through the opening is inserted into the second ferrule to fix the optical fiber. The optical fiber without deflection is contained in the package by making a first expansion/contraction amount created due to the thermal expansion of the package and the thermal expansion of the pipe match a second expansion/contraction amount created due to the thermal expansion of the optical fiber and the thermal expansion of the second ferrule.

Optical integrated device

An object of the invention is to provide a small size Faraday rotator which is easy to produce and enables reliable reduction of temperature dependence of the Faraday rotation angle, by defining the crystal orientation and arrangement order of each Faraday element when three or more Faraday elements are used. For this purpose, a Faraday rotator of the present invention comprises: a Faraday element section being composed of a plurality of Faraday elements, a permanent magnet for applying a magnetic field to each Faraday element in a parallel direction to an optical axis direction, and an electromagnet for applying a variable magnetic field in a perpendicular direction to the optical axis direction, wherein each Faraday element is arranged such that the crystal orientation of each is perpendicular to a light beam direction, and crystal orientations of adjacent Faraday elements are opposed to each other.

Faraday rotator

The present invention aims at providing a variable optical attenuator to achieve the reduction of the wavelength-dependency of the entire device, by optimizing the magneto-optical system of the variable optical attenuator by deliberating the wavelength-dependency of Faraday rotation angles. To this end, the variable optical attenuator according to the present invention comprises: a Faraday rotator for providing a variable Faraday rotation angle; and a polarizer and an analyzer arranged in front of and behind the Faraday rotator, respectively, wherein the angle formed between the optical axis of the analyzer and the optical axis of the polarizer is set such that the Faraday rotation angle at which the wavelength-dependency of the optical attenuation amount of the variable optical attenuator becomes the maximum, is brought to be substantially 0&deg;, to thereby reduce the wavelength-dependency of the optical attenuation amount at the aforementioned Faraday rotation angle.

Variable optical attenuator utilizing Faraday effect

Non-digging tube reverse lining engineering method of conduit

Growing community of inventors

Kawasaki, Japan

Seiichi Ikeda