Nippon Telegraph and Telephone Corporation

Japan Aviation Electronics Industry, Limited

Hiroaki Hanafusa

Juichi Noda

Yoshiaki Takeuchi

Hiroyuki Sasaki

Masato Shimamura

Nobuo Tomita

Taisuke Oguchi

Shiro Nishi

Itaru Yokohama

Mitsuhiro Tateda

Noriyoshi Yamada

Yamada Noriyoshi

Kazunori Chida

A dielectric multilayer filter applicable to optical communication systems is disclosed, as is a fabrication method therefor, and an optical element incorporating the same. The disclosed dielectric multilayer filter includes a fluorinated polyimide base layer with a dielectric multilayer formed thereover. According to the disclosed fabrication method, a fluorinated polyimide layer is formed by applying liquid fluorinated polyimide material over a smooth surface to a predetermined thickness followed by drying and hardening, after which a dielectric multilayer is formed over the fluorinated polyimide layer by an ion assist vapor deposition method, and then stripping the fluorinated polyimide layer away from the underlying smooth surface. The disclosed dielectric multilayer filter can be easily and economically produced at a suitably small thickness with no need for grinding, exhibits highly uniform physical and optical properties, and is exceedingly durable and resistant to curling and warping.

Method of fabricating a dielectric multilayer filter

Dielectric multilayer, filter, manufacturing method therefor, and

Two single mode optical fibers are reduced in diameter over a predetermined length to form reduced-diameter portions whose center portions have different diameters. The two optical fibers are intersected at a small angle to each other substantially centrally of their reduced-diameter portions and then are fused together at the intersecting portions and the fused portions of the two optical fibers are heated and stretched to provide an optical coupler having a desired coupling ratio.

Wide-band optical fiber coupler and its manufacturing method

Two single mode optical fibers are stretched to form prestretched portions of different diameters, and then the optical fibers are fused together at their prestretched portions to form a coupling region which is stretched to obtain a wide-band optical fiber coupler of a desired splitting ratio.

In a method of making an optical fiber coupler through heat elongation of optical fibers, the performance of the coupled optical fibers is measured after the optical fibers are heat elongated at least once, and based on the measured elongation length and the performance of the coupled optical fibers, a functional equation representing their relationship is determined by approximate calculation. The functional equation is used to calculate an elongation length which provides the intended performance of the coupled optical fibers, and then the optical fibers are heat elongated to the calculated length.

Method for the manufacture of an optical fiber coupler

A fiber coupler includes first and second optical fiber groups and a fused-elongated region. The first optical fiber group is obtained by parallelly arranging a plurality of optical fibers on a single plane, a coating of each of the optical fibers being removed throughout a predetermined portion at the same position as that of an adjacent optical fiber in a longitudinal direction. The second optical fiber group is obtained by parallelly arranging adjacent optical fibers on a predetermined plane parallel to an arrange plane of the first optical fiber group at the same pitch as that of the first optical fiber group, a coating of each of the optical fibers being removed throughout a predetermined portion at the same position as that of an adjacent optical fiber in a longitudinal direction as the first optical fiber group. The fused-elongated region is located at a portion of the predetermined portions from which the coatings are removed and obtained by fusing/elongating at least some optical fibers of the first optical fiber group with at least some optical fibers of the second optical fiber group so that corresponding optical fibers are fused/elongated. A plane including centers of two cores of the optical fibers fused with each other at the fused-elongated region is arranged substantially perpendicular to the arrange planes of said first and second optical fiber groups, and at least a portion of the first and/or second optical fiber groups is a fiber ribbon obtained by integrally forming a plurality of optical fibers each having a core and a clad by a coating.

Fiber coupler and method and apparatus for manufacturing the same

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Mito, Japan

Hiroaki Hanafusa