Nippon Telegraph and Telephone Corporation

Itaru Yokohama

Koji Yamada

Junichi Takahashi

Shoichi Sudo

Satoru Tomaru

Juichi Noda

Akihiko Shinya

Masaya Notomi

Kazunori Naganuma

Yoshihisa Sakai

Yoshiaki Takeuchi

Toshikuni Kaino

Hiroaki Hanafusa

Mitsuhiro Tateda

Shigeo Ishibashi

Yuzo Ishida

Yuzo Yoshikuni

Kenichi Kubodera

Tetsuhiko Ikegami

Hiroshi Yasaka

Atsushi Yokoo

Kazunori Chida

Chiharu Takahashi

A two-dimensional photonic crystal slab waveguide is provided in which a line defect is formed, wherein a first width which is a distance between centers of nearest two lattice points located on both sides of the line defect is different from a second width which is a corresponding distance in a normal two-dimensional photonic crystal slab waveguide. In addition, a two-dimensional photonic crystal slab waveguide is provided in which low refractive index columns in a optical waveguide part are placed at positions shifted from normal positions in a normal two-dimensional photonic crystal slab.

Photonic crystal waveguide

Of hydrogen atoms constituting 2-adamantylamino-5-nitropyridine, at least hydrogen atom of N--H part is substituted with deuterium to obtain a deuterated AANP. An organic optical material is made from the deuterated AANP. Content of the deuterated AANP in this case is preferably more than 25%. With this method, an organic nonlinear optical material can be provided for devices having a large wavelength conversion efficiency in wavelength conversion relating to optical communications wavelength region, particularly at and around 1.55 .mu.m wavelength.

Deuterated 2-adamantylamino-5-nitropyridine, organic nonlinear optical

According to the process of the present invention for producing a garnet single crystal fiber, a crystal is grown while the direction of a seed crystal, corresponding to the direction of growth, is set in a direction having angles of at least 10.degree. from a direction equivalent to the &lt;100&gt; orientation, at least 20.degree. from a direction equivalent to the &lt;110&gt; orientation and at least 20.degree. from a direction equivalent from the &lt;211&gt; orientation. The resulting garnet single crystal fiber does not include a core, which is formed due to facet formation, and has an excellent optical homogeneity necessary for use in an optical device such as a laser device or an isolator.

Process for producing garnet single crystal

A method of stabilizing the frequency of a semiconductor laser comprises stabilizing a time-dependent frequency fluctuation by utilizing an optical energy absorption medium including an isotope acetylene gas molecule. An apparatus for stabilizing the frequency of a semiconductor laser, comprises a semiconductor laser, an optical energy absorption medium, a photodetector and a control circuit as essential elements. The optical energy absorption medium includes an isotope acetylene molecule.

Method and apparatus for stabilizing frequency of semiconductor laser

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

Isehara, Japan

Itaru Yokohama