Nippon Telegraph and Telephone Corporation

Ando Electric Company

Mitsuhiro Tateda

Tsuneo Horiguchi

Juichi Noda

Yoshiaki Takeuchi

Hiroaki Hanafusa

Itaru Yokohama

Katsusuke Tajima

Masaharu Ohashi

Kazuyuki Shiraki

Tekken Ri

Satohi Matsuura

Kazunori Chida

A high-power acceptable optical fiber comprises a core and cladding provided on the outer peripheral surface of the core. The dopant concentrations in the core and cladding each change in the axial direction of the optical fiber. The core has a same relative refractive index profile in any cross section thereof taken in a direction perpendicular to the axial direction thereof. The relative refractive index profile is normalized by a maximum refractive index of the core.

High power acceptable optical fiber and fabrication method thereof

A light source which is stabilized in frequencies at uniform intervals comprises a light source 5 whose light frequency is varied with a signal from a reference signal source 4; a frequency detector 6 for detecting the frequency of the output of the light source 5, the cycles of the said frequency detector being the same as the uniform intervals; a comparator 2 for comparing the output of the frequency detector 6 and the output of the reference light source 1; and a switch 3 having as its input the output of the comparator 2 for inputting the output to the light source 5, said switch being so operated that when the frequency of the light source 5 is to be changed the switch is opened and the output of the reference signal source 4 is changed to set the output frequency of the light source 5 near the desired frequency and then the switch 3 is closed.

Frequency stabilized light source

Use is made of a non linear interaction between a first modulated signal light from a first light source and a second signal light from a second light source which propagate in an optical fiber to be examined in opposite directions, i.e., so-called Brillouin light amplification, to analyze the signal waveform of the second signal light, which is influenced by the action of such light amplification.

Optical fiber evaluation method and system

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

Growing community of inventors

Mito, Japan

Mitsuhiro Tateda