Nippon Telegraph and Telephone Corporation

The Furukawa Electric Co., Ltd.

Takayoshi Mori

Taiji Sakamoto

Masaki Wada

Kazuhide Nakajima

Takashi Yamamoto

Azusa Urushibara

Shinichi Aozasa

Ryuichi Sugizaki

Katsunori Imamura

Fumihiko Yamamoto

Tomohiro Gonda

An optical amplifier of the present disclosure includes an optical resonator that includes an amplification fiber capable of amplifying signal light having one or more propagation modes and resonates at least one propagation mode of the signal light amplified by the amplification fiber; an excitation light source that outputs excitation light for exciting the amplification fiber; and a multiplexer that multiplexes the signal light and the excitation light, in which the optical resonator includes a gain clamp setting unit which sets gain clamp for at least one propagation mode out of a plurality of propagation modes resonating in the optical resonator.

Optical amplifier

The optical fiber of the present invention includes a core, and a cladding that is provided on an outer periphery of the core and has a refractive index lower than a refractive index of the core region. In the optical fiber of the present invention, a V value representing a normalized frequency of an LPmode is greater than or equal to 4.8 and less than or equal to 6.4.

Optical fiber and optical transmission system

The optical fiber according to the present disclosure is an optical fiber having a pure silica core which is a step index core through which an LPm1 mode with an effective area of 250 &#x3bc;mor more is propagated by setting a relative refractive index difference to 0.60% or less, considering an effective cutoff condition, and only 2 or more modes or the LPm1 mode are propagated, with the optical fiber as the transmission line.

A differential mode attenuation compensator includes a first multi-mode optical fiber and a third multi-mode optical fiber in which a plurality of propagation modes propagate in a wavelength of a propagating optical signal; and a second multi-mode optical fiber including a core and a clad and arranged with a central axis aligned between the first multi-mode optical fiber and the third multi-mode optical fiber, in which each loss in the plurality of propagation modes is different in the first multi-mode optical fiber and the third multi-mode optical fiber.

Inter-mode loss difference compensator and optical amplifier

An optical transmission system according to the present disclosure is a mode multiplexed optical transmission system using a multi-mode optical fiber in which a plurality of propagation modes propagate as a transmission line, the optical transmission system including an optical fiber transmission line () that includes an optical fiber with two or more propagation modes; and a plurality of mode converters () that are configured to generate mode coupling between at least one pair of the propagation modes, in which a variation in an installation interval of the plurality of mode converters () is equal to or less than a threshold value determined by the transmission line length (Lt) of the optical fiber transmission line ().

Optical transmission system

A multicore fiber includes a plurality of unit multicore fibers each including: a plurality of core portions; and a clad portion which is formed in an outer circumference of the core portions and has a refractive index lower than a maximum refractive index of the core portions. The plurality of the core portions have substantially same refractive index profile and different group delays at same wavelength in same propagation mode. The core portions of the multicore fiber are configured so that the core portions of the plurality of the unit multicore fibers are connected in cascade, a maximum value of differential group delays between the core portions of the multicore fiber is smaller than a reduced value of a maximum value of differential group delays between the core portions of each unit multicore fiber as a value in terms of a length of the multicore fiber.

Growing community of inventors

Tsukuba, Japan

Takayoshi Mori