Abstract: A controller supplies a driving signal to an optical modulator for modulating light from a light source in accordance with the driving signal, a low frequency signal being superposed on the driving signal. A bias unit monitors a low frequency component of the modulated light and controls bias of the optical modulator. A compensation unit controls the intensity of the light so as to compensate for refractive index variation of the optical modulator which is caused by variation of the bias.

Abstract: An amount of ASE generated changes due to a temperature and respective powers of signals input to and output from an optical amplifying unit, causing a fluctuation of a gain of the optical amplifying unit. A photodiode on an input side and a photodiode on an output side detect the input and output powers, and temperature detecting unit detects an operating temperature of the optical amplifier. A control unit corrects the amount of ASE generated, based on at least one of the detected input and output signal powers and on the detected temperature according to AGC control, which controls driving of an excitation LD for the optical amplifier to keep a gain of the optical amplifier constant.

Abstract: A Raman amplifier providing a wideband gain for use in a wavelength division multiplexing (WDM) optical communication system. In one embodiment, a first optical amplifier Raman amplifies a wavelength division multiplexed signal light in both a first wavelength band and a second wavelength band in accordance with a plurality of excitation (pumping) lights provided to the first optical amplifier, the first and second wavelength bands being different from each other. A divider divides the amplified signal light into first and second lights in the first and second wavelength bands, respectively. A second optical amplifier amplifies the first light and has a gain band in the first wavelength band. The third optical amplifier amplifies the second light and has a gain in the second wavelength band. In various embodiments, a gain equalizer and/or an optical isolator is used in combination with the first optical amplifier providing the Raman amplification.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: An amplification medium is inputted thereto first lights and second lights, polarizations of which are orthogonal. A pumping means inputs first pump lights coinciding with the polarization of the first lights, and second pump lights coinciding with the polarization of the second lights to the amplification medium. The gain of a wavelength or wavelength band of a certain light can be efficiently controlled, simply and independently, without affecting the other wavelengths or wavelength bands.

Abstract: A light amplification control unit whereby the gain of an optical amplifier can be controlled with ease. A plurality of pump light sources each generate a pump beam having the effect of amplifying a signal beam, and an external control light source generates an external control beam having a wavelength that influences the signal beam amplification effect by means of the pump beams. A multiplexing section multiplexes the pump beams with the external control beam and causes the multiplexed beams to enter an optical fiber in a direction opposite to that of the signal beam. A control section controls the output of the external control beam from the external control light source, whereby the gain of the signal beam amplified by the pump light sources can be controlled.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: An amplification medium is inputted thereto first lights and second lights, polarizations of which are orthogonal. A pumping means inputs first pump lights coinciding with the polarization of the first lights, and second pump lights coinciding with the polarization of the second lights to the amplification medium. The gain of a wavelength or wavelength band of a certain light can be efficiently controlled, simply and independently, without affecting the other wavelengths or wavelength bands.

Abstract: An amount of ASE generated changes due to a temperature and a signal input power of an optical amplifying unit and causes a fluctuation of a gain of the optical amplifying unit. A photodiode on an input side and a photodiode on an output side detect input and output powers, and a temperature detecting unit detects a temperature of an optical amplifier. A control unit corrects the amount of ASE generated based on the detected input and output powers and the temperature according to AGC control. Driving of an excitation LD is controlled by a corrected result, and a gain of the optical amplifier is kept constant.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: The present invention aims at providing an optical amplification apparatus for improving noise characteristics by controlling an amplification operation by assuming a noise figure of the overall apparatus and by taking influences of noise light due to Raman amplification into consideration, and a controlling method of the optical amplification apparatus.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: An object of the invention is to provide an optical amplification apparatus using Raman amplification, which can reliably judge an input interruption of signal light and can shut down the supply of excitation light in accordance with a judged input interruption of the signal light. To this end, the optical amplification apparatus of the present invention comprises an input interruption detection means for detecting a noise light component due to the Raman amplification, and judging an input interruption of the signal light based on the detection result, and further comprises a shut down control means for shutting down supply of the excitation light when an input interruption of the signal light is judged by the input interruption detection means.

Abstract: A light amplification control unit whereby the gain of an optical amplifier can be controlled with ease. A plurality of pump light sources each generate a pump beam having the effect of amplifying a signal beam, and an external control light source generates an external control beam having a wavelength that influences the signal beam amplification effect by means of the pump beams. A multiplexing section multiplexes the pump beams with the external control beam and causes the multiplexed beams to enter an optical fiber in a direction opposite to that of the signal beam. A control section controls the output of the external control beam from the external control light source, whereby the gain of the signal beam amplified by the pump light sources can be controlled.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: An object of the invention is to provide an optical amplification apparatus using Raman amplification, which can reliably judge an input interruption of signal light and can shut down the supply of excitation light in accordance with a judged input interruption of the signal light. To this end, the optical amplification apparatus of the present invention comprises an input interruption detection means for detecting a noise light component due to the Raman amplification, and judging an input interruption of the signal light based on the detection result, and further comprises a shut down control means for shutting down supply of the excitation light when an input interruption of the signal light is judged by the input interruption detection means.

Abstract: The present invention aims at providing an optical amplification apparatus for improving noise characteristics by controlling an amplification operation by assuming a noise figure of the overall apparatus and by taking influences of noise light due to Raman amplification into consideration, and a controlling method of the optical amplification apparatus.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: The present invention aims at providing an optical amplification apparatus for improving noise characteristics by controlling an amplification operation by assuming a noise figure of the overall apparatus and by taking influences of noise light due to Raman amplification into consideration, and a controlling method of the optical amplification apparatus.