Fujitsu Corporation

Sumitomo Electric Industries, Limited

Fujitu Limited

Junichi Kumasako

Takafumi Terahara

Hiroki Ooi

George Ishikawa

Kentaro Nakamura

Tomoo Takahara

Rainer Hainberger

Takashi Iwabuchi

Motoki Kakui

Tetsufumi Tsuzaki

In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.

Chromatic dispersion compensating apparatus

In a WDM transmission system employing a plurality of short wavelength bands having great attenuation due to optical fiber transmission, an optical repeater is constructed of a first multiplexing section and a second multiplexing section. The first multiplexing section is used for wavelength-multiplexing both the excitation light from a first Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The second multiplexing section is used for wavelength-multiplexing both the excitation light from a second Raman excitation light source, which distributively amplifies an S+ band included in light propagating through an optical fiber, and the light propagating through the optical fiber. The first and second multiplexing sections are provided between the optical fibers disposed between end offices. Thus an equal and satisfactory optical SN ratio even at any band are obtained.

Optical transmission system, optical repeater, and optical transmission method

The present invention relates to a Raman amplifier where flexibility in device design considering both of Raman amplification and dispersion compensation is high. In the Raman amplifier, the Raman amplification optical fiber included in the optical amplification section and the dispersion compensating optical fiber included in the dispersion compensation section are arranged while being optically connected to each other. Since the optical amplification section and the dispersion compensation section are provided as independent optical devices, one device can be designed without being restricted to the design conditions of the other device.

Raman amplifier and optical communication system including the same

Different bands (C-band and L-band) are allotted respectively to an upstream optical signal and a downstream optical signal. In a transmission-path optical fiber for Raman amplification, the C-band optical signal is amplified by pumping light from a C-band pumping light source, and the L-band optical signal is amplified by pumping light from an L-band pumping light source. As a result of this configuration, the optical signals are Raman-amplified through backward pumping in both upstream and downstream directions, whereby negative effects, which could be exerted on the optical signals by forward pumping, can be avoided.

Bidirectionally transmittable optical wavelength division multiplexed transmission system

The present invention aims at providing an optical transmission system for improving transmission characteristics, taking account of the nonlinear optical effect to be caused not only in an optical fiber transmission path wherein the distributed Raman amplification is performed but also in an amplifying medium wherein the discrete Raman amplification is performed, within an optical transmission device. To this end, the optical transmission system of the present invention controls, in each repeating section, the supplying conditions of pumping lights at a distributed Raman amplifier and a discrete Raman amplifier, based on signal light powers at a signal light input point to the optical fiber transmission path and a signal light output point from the optical fiber transmission path, and signal light powers at a signal light input point to a DCF (amplifying medium) and a signal light output point from the DCF within an optical repeater, so that an amount of nonlinear optical effect caused in one repeating section is brought to a required value or less.

Growing community of inventors

Kawasaki, Japan

Junichi Kumasako