Fujitsu Corporation

Yoshio Nabeyama

Mitsuo Kitamura

Kazuyuki Tanikawa

Kenji Ohta

Hirofumi Araki

WDM optical tranmsmission equipment with redundant configuration includes a plurality of tranmitters. Each tranmitter includes active and standby panels including active and standby optical transmission circuits respectively having active and standby attenuators for controlling an attenuation amount of each output of the active and standby optical transmission circuits; and a coupler combining the outputs of the active and standby attenuators. An output light wavelength of the standby optical transmission circuit is set to a set wavelength different from the output light wavelength of the active optical transmission circuit, and the attenuation amount of the standby attenuator is set to the maximum, and the standby panel is set, and subsequently, the set wavelength of the output light of the standby optical transmission circuit is set to a target wavelength identical to the output light wavelength of the active optical transmission circuit, each having, and a wavelength control method of the light output in the standby system. The problem is solved of the light emitted in a standby system as affecting an active system, while the active system is in operation.

WDM optical transmission equipment with redundant configuration, and wavelength control method of light output in standby system

An optical amplifier with redundant excitation light sources for exciting a rare earth doped optical fiber such as an EDF (Erbium Dope Fiber) minimizes the loss of the excitation light so as to introduce the excitation light to the EDF effectively, though an optical coupler, which plural optical fibers for transmitting the excitation lights from plural excitation light sources are welded, is used. And, the optical amplifier keeps the total of the excitation light introduced to the EDF at a predetermined value and changes one excitation light source to the other unless the output total from the respective excitation light sources becomes zero.

Optical amplifier and optical transmission system

Disclosed is a method and apparatus for preventing the occurrence of surge light that may be caused by an off-to-on transition of input signal light in an optical amplifier using an erbium-doped optical fiber. An input electrical signal, optical modulator output, leakage light, or light output is monitored to detect the off-to-on transition of the signal light, and the energy level of the input signal light or pumping light is gradually increased from a low level to an operating level.

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Yokohama, Japan

Yoshio Nabeyama