| 摘要 |
PROBLEM TO BE SOLVED: To obtain an OADM that suits the construction of an optical communication network, especially of an NB-WDM system by separating a wavelength multiple optical signal to an optical signal of each wavelength with a demultiplexer and inserting a light switch and an output fixing controlling part into a transmission line of an optical signal of each separated wavelength. SOLUTION: Variable optical attenuators 4-1 to 4-n into which an optical signal of each wavelength is inputted are subjected to feedback control so that the light quantity of their output light can be constant, and also light switches 3-1 to 3-n are respectively inserted into an optical path of the optical signal of each wavelength so that the intensity level of the optical signal of an optional wavelength can be decreased or increased. A light quantity detection circuit 10 is provided with a circuit to respective optical branches and an attenuator control circuit 9 is provided with a control circuit that corresponds to an output of each light quantity detection circuit 10 and controls variable optical attenuators 4-1 to 4-n corresponding to each optical branch. Also, each optical signal that is separated to optical signals of respective wavelengths by a demultiplexer 2 goes through light switches 3-1 to 3-n. |
