Fujitsu Corporation

Masao Nakata

Yoshio Shimano

Maki Hiraizumi

Norifumi Shukunami

Kosuke Komaki

Tatsuya Tsuzuki

Yuji Tamura

Takashi Satou

An amplifier includes a first monitor configured to measure first optical power including first signal light and ASS light of a first wavelength band propagated through the amplification medium, and a processor configured to calculate the first ASS light power corresponding to the first excitation light power, based on the determined first model formula, calculate the second ASS light power corresponding to the second excitation light power, based on the determined second model formula, calculate the first signal light power by subtracting the calculated first ASS light power and second ASS light power from the first optical power measured by the first monitor, and calculate a difference between the calculated first signal light power and first target signal light power, and controll a first excitation light source or a second excitation light source to adjust the first excitation light power or the second excitation light power based on the difference.

Raman optical amplifier and raman optical amplification method

There is provided an optical amplifier, which includes: an optical amplification medium; a pump light generator configured to generate pump light with a power corresponding to a set control value and supply the generated pump light to the optical amplification medium; a first controller including a level control circuit configured to generate the control value such that an output power of the optical amplification medium approaches a target power, and a limiter configured to limit a range of the control value in variable; and a latch circuit configured to set a specific control value to the pump light generator during a period in which the first controller is in a stop state.

Optical amplifier

A transmission device includes an optical amplifier to amplify an optical main signal to be transmitted on an optical transmission path; a first controller to stop output of the optical amplifier and output of an optical monitor signal to be transmitted on the optical transmission path when a failure of the optical transmission path is detected; a second controller to be switched from the first controller and to operate and stop the output of the optical amplifier and the output of the optical monitor signal when the failure of the optical transmission path is detected; an optical monitor signal transceiver to transmit and receive the optical monitor signal including control information; and a switch to switch an operation from the first controller to the second controller, based on information of the failure of the optical transmission path based on the states of transmission and reception of the optical monitor signal.

Transmission device and transmission system

An optical receiving apparatus includes an optical amplification medium that receives an excitation light and an input light, an optical loss medium that receives an output light from the optical amplification medium, a monitor that detects a power level of an output light from the optical loss medium, a controller that controls a power of the excitation light such that the power level of the output light detected by the monitor is at a target value, and a receiver that receives the output light from the optical loss medium, the output light not being optically amplified.

Optical receiving apparatus and optical amplifying apparatus

A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Raman amplifier and raman amplifier adjustment method

A Raman amplifier that amplifies a signal light intensity by using a Raman amplification effect of an optical fiber transmission channel has an excitation unit that supplies excitation lights of a plurality of wavelengths to the optical fiber transmission channel and performs Raman amplification, a signal light monitor that monitors the signal light intensity of each wavelength contained in the signal light that is Raman amplified, an output light intensity deviation monitoring circuit that finds a deviation in the intensity of each signal light detected by the signal light monitor, and an excitation light control circuit that controls an excitation light intensity from excitation light sources of each wavelength constituting the excitation unit so as to correspond to a predetermined characteristic based on a deviation of the intensity of signal light found by the output light intensity deviation monitoring circuit.

Raman amplifier for amplifying signal light for optical communication, optical communication system equipped with Raman amplifier, and method for controlling Raman amplifier

According to an aspect of the embodiment of the invention, an optical amplifier including an input port, an output port, a plurality of amplifying parts, an optical attenuator, a gain controller and an optical attenuator controller. The plurality of amplifying parts includes an optical amplification medium and a pumping light source for generating pump light. The optical attenuator is optically connected between the amplifying parts. The gain controller controls the pump light power of the pump sources, respectively, in such a way that the ratio decreases in accordance with the gain set value increasing and the ratio interpose between a first threshold level and a second threshold level. The optical attenuator controller controls attenuation of the optical attenuator in order to maintain the sum of generating gains of the amplifying parts in the gain set value in accordance with a state of the signal light inputted into the input port.

Multistage optical amplifier with gain control using pump ratio

When pump light is supplied to a transmission line fiber from a downstream station toward an upstream station and signal light from the upstream station is Raman-amplified, a corresponding intensity of amplified spontaneous scattering light is calculated from a required Raman gain by using a correlation between a Raman gain and the intensity of amplified spontaneous scattering light that occurs with Raman amplification, and further a target light intensity is calculated from the obtained intensity of the amplified spontaneous scattering light and the intensity of the amplified signal light. Then, the intensity of the pump light is controlled so that the intensity of light, which is measured by the downstream station, becomes equivalent to the target light intensity.

Raman amplifier

Raman amplifier and Raman amplifier adjustment method

An optical amplifier that improves transmission quality by driving an excitation light source according to a change in the level of an input optical signal and by compensating for a change in the characteristics of the excitation light source. An optical amplification section includes an amplification medium doped with an active substance for optical amplification and an excitation light source for emitting excitation light. A constant-gain control section finds out target excitation light power to be set according to a change in the level of an input optical signal on the basis of a correlation between a gain and excitation light power to obtain a target gain, finds out a target drive signal for making the excitation light source emit the target excitation light power on the basis of a correlation between a drive signal for driving the excitation light source and excitation light power, and exercises constant-gain control over the optical amplification section by a feedforward control system.

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Kawasaki, Japan

Masao Nakata