Patent ID: 8320771
Filing Date: 2012-11-27
Classification: H04J

Abstract:
1. An optical transmission system comprising: a transmitter that transmits a wavelength-division-multiplexed optical signal having a plurality of optical signals of different wavelengths multiplexed at an upstream side of an optical transmission direction; a transmitting unit that transmits the wavelength-division-multiplexed optical signal transmitted by the transmitter; a plurality of repeaters that amplifies the wavelength-division-multiplexed optical signal transmitted by the transmitting unit; and a receiver that receives the wavelength-division-multiplexed optical signal transmitted by the transmitting unit via the repeaters at a downstream side of the optical transmission direction, wherein each of the repeaters comprises: a variable optical attenuating unit that collectively attenuates the wavelength-division-multiplexed optical signal input thereto from an upstream side; an optical-attenuation adjusting unit that adjusts attenuation of a signal level of the wavelength-division-multiplexed optical signal in the variable optical attenuating unit; and an optical amplifying unit that collectively amplifies the wavelength-division-multiplexed optical signal collectively attenuated by the variable optical attenuating unit, at a predetermined amplification gain, and outputs to a downstream side the wavelength-division-multiplexed optical signal collectively amplified, and the optical-attenuation adjusting unit comprises: an input level detector that detects a signal level of the wavelength-division-multiplexed optical signal collectively attenuated by the variable optical attenuating unit; an output level detector that detects a signal level of the wavelength-division-multiplexed optical signal, which is amplified by the optical amplifying unit and output to a downstream side; an output-level transmitting unit that receives information of a signal level of the wavelength-division-multiplexed optical signal from the output level detector and transmits information of the signal level of the wavelength-division-multiplexed optical signal detected by the output level detector to a repeater adjacent at a downstream side; and an attenuation amount controller that controls the variable optical attenuating unit by calculating an attenuation amount of a signal level of the wavelength-division-multiplexed optical signal in the variable optical attenuating unit based on information of a signal level of the collectively attenuated wavelength-division-multiplexed optical signal detected by the input level detector and a signal level of the wavelength-division-multiplexed optical signal transmitted by the output-level transmitting unit of a repeater adjacent at an upstream side.