Patent ID: 7725034
Filing Date: 2010-05-25
Classification: H04B

Abstract:
1. An optical transmission apparatus for outputting wavelength-division multiplexed signal light received together with supervisory signal light to an optical transmission path of a next section with a predetermined optical power, comprising: a first detecting unit for separating the supervisory signal light from the received wavelength-division multiplexed signal light and detecting the power of the supervisory signal light; a second detecting unit for detecting the power of the wavelength-division multiplexed signal light after separating the supervisory signal light; a gain control type optical amplifier for amplifying the wavelength-division multiplexed signal light; an optical attenuator, variable in extent of attenuation, for adjusting the power level of the wavelength-division multiplexed signal light outputted from said optical amplifier; and a monitor and control unit for controlling the optical amplifier so as to keep a constant gain and controlling the optical attenuator so that output level of the wavelength-division multiplexed signal light has a predetermined target value, wherein; the monitor and control unit compares the power of the supervisory signal light detected by the first detecting unit with a first higher limit value and a first lower limit value that define a permissible fluctuation range of the supervisory signal light, monitors the fluctuation of the power of wavelength-division multiplexed signal light detected by the second detecting unit, and controls execution of output level control by the optical attenuator based on the results of the comparing and monitoring.