Fujitsu Corporation

Kazuya Amaki

Masaaki Takahashi

Takeo Osaka

Takanori Maki

Mitsushi Nitta

Satoru Miyazaki

Katsumi Kikawa

In a light amplifier device having a rare-earth element doped optical fiber to which an input light signal and an exciting light are applied, an exciting-light emitting part generates the exciting light. A variable attenuator which attenuates the exciting light applied. A driving part which supplies a driving current to the exciting light part. A monitor part monitors the input light signal. A light-emitting part generates a light in a wavelength band which includes a wavelength of the input light signal. A control part for controlling either the attenuator or driving part, when the monitor part detects a change in the input light signal, so that the light generated by the light-emitting part is applied to the rare-earth element doped optical fiber.

Light amplifier device capable of suppressing light surge

An optical amplifying repeater is provided whereby a transfer signal generated in response to a monitor signal from an end office is generated and amplified by a rare earth element doped fiber, the modulation degree with respect to the optical output of the fiber being held constant, regardless of the frequency of the this transfer signal. This optical amplifying repeater has a rare earth element (such as erbium) doped fiber, an automatic adjusting loop 12, and a monitor and response unit, and is further provided with a modulation degree compensation part for the purpose of holding constant the transfer signal modulation degree with respect to the optical output of the fiber, regardless of the frequency of the transfer signal.

Optical amplifying repeater

An optical repeater having a loop-back function is provided in a transmission system including first and second transmission lines. The optical repeater includes a first optical amplifier connected to the first transmission line, a second optical amplifier connected to the second transmission line, a loop-back unit connected to both transmission lines, and a control unit. The control unit controls the loop-back unit to form a loop-back line when a loop-back instruction is detected. Therefore, optical signals are directly amplified without being converted into electrical signals, and a loop-back signal (return signal) and optical signals are not mixed in the optical repeater so that a loop-back operation can be correctly carried out in an optical repeater having a small size and low power consumption.

Growing community of inventors

Kawasaki, Japan

Kazuya Amaki