Nippon Telegraph and Telephone Corporation

Hitachi Cable, Inc.

Yasuo Kimura

Katsuyuki Imoto

Masataka Nakazawa

Seiichi Kashimura

Toshikazu Kamoshida

Fujio Kikuchi

A core waveguide having a substantially rectangular cross section, with the width thereof greater than the thickness thereof, is provided in a cladding formed on a substrate, and a rare earth element-doped layer is provided in the core waveguide along the waveguiding direction of the waveguide. With the width of the core waveguide set greater than the thickness of the core waveguide, good optical confinement in the width direction of the waveguide is obtained, which enables light to be absorbed by the rare earth element-doped layer efficiently and concentratedly. It is thereby possible to achieve a marked improvement in the excitation efficiency of excitation power. Thus, an enhanced excitation efficiency is achieved with less addition of a rare earth element, and a high-gain optical amplification waveguide free of concentration extinction is provided.

Rare earth element-doped optical waveguide and process for producing the

An optical waveguide star coupler includes a light propagating core provided on a substrate. An exciting light and a signal light are supplied to the light propagating core. The light propagating core includes a plurality of Y-branching waveguides connected one after another to provide a multi-stage waveguide structure. A signal light inputted in the core is combined during the propagation through the core with the exciting light so that the signal light is amplified.

Optical waveguide type star coupler

Growing community of inventors

Ibaraki, Japan

Yasuo Kimura