Optical add-drop device

The self-oscillation frequencies of injection-locked laser devices 5-1 through 5-M are preset to the frequency of the signal light to be transmitted by the optical add-drop device, and the self-oscillation frequencies of the injection-locked laser devices 6-1 through 6-N are preset to the frequency of the signal light to be branched by this device. Wavelength-division multiplexed signal light inputted from an input optical line 1 is split in an optical splitter 2 and inputted to the injection-locked laser devices. Signal light whose wavelength has been set for the injection-locked laser devices 5-1 through 5-M is amplified by these injection-locked laser devices 5-1 through 5-M and inputted to an optical combiner 10. Signal light whose wavelength has been set for the injection-locked laser devices 6-1 through 6-N is outputted to branching optical lines 8-1 through 8-N. Signal light outputted from inserting optical lines 9-1 through 9-L is inputted to the optical combiner 10 together with the signal light from the injection-locked laser devices 5-1 through 5-M and is outputted to an output optical line 11. It is thus possible to provide an optical add-drop device in which the wavelength and number of split or inserted signal light can be set as needed.