Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Hokkaido University

Takeshi Fujisawa

Kunimasa Saitoh

Kazuhide Nakajima

Takashi Matsui

Taiji Sakamoto

Naoki Fujiwara

Kyozo Tsujikawa

Takuo Hiratani

Takanori Sato

An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, a second waveguide optically coupled to the first loop mirror and the second loop mirror, a first access waveguide optically coupled to the first waveguide, a second access waveguide optically coupled to the second waveguide, and an output section, wherein the first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer, the second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer, the output section includes a third loop waveguide, a third multiplexer/demultiplexer, a third waveguide, and a fourth waveguide, the third loop waveguide optically coupled to the second loop waveguide and the third multiplexer/demultiplexer, the third waveguide and the fourth waveguide optically coupled to the third multiplexer/demultiplexer, and the output section.

Optical filter and wavelength tunable laser element

An object of the present invention is to provide a multi-core optical fiber that can prevent an increase in bending loss even when a distance between a peripheral core and a cladding boundary is decreased, and can improve a bending loss characteristic in a state where an influence on a cutoff wavelength and a mode field diameter is small, and a design method thereof. The multi-core optical fiber according to the present invention is an optical fiber in which two or more core regions are arranged in a cladding region having a refractive index lower than a refractive index of the core at a minimum core interval, a ring-shaped low refractive index region surrounding the core and having a refractive index lower than the refractive index of the cladding region is provided, a bending loss after the provision of the ring-shaped low refractive index region is reduced as compared with a characteristic in a case where the ring-shaped low refractive index region is not provided, and at the same time, a change in mode field diameter after the provision of the ring-shaped low refractive index region is not changed as compared with a characteristic in a case where the ring-shaped low refractive index region is not provided.

Multicore optical fiber and design method

Growing community of inventors

Sapporo, Japan

Takeshi Fujisawa