of employing broadband light sources as downstream light sources injection light having a wide line width generated from the first broadband light source 210 is delivered to a second interleaver 206 from a first wdm filter 207 through a circulator 208 in this case interleavers 205 206 213 and 214 are elements for outputting an input light through two output ports by splitting the input light into odd channels and even channels the interleavers 205 206 213 and 214 employed according to an embodiment of the present invention operate based on channels substantially identical to channels of muxs de muxs 203 204 215 and 216 in addition the muxs de muxs 203 204 215 and 216 employed according to this embodiment of the present invention have two input output ports at one side of the muxs de muxs 203 204 215 and 216 in the 2 u00d7 n shape in addition injection light output to an even port of the second interleaver 206 is divided into channels according to its wavelength s and output in the first mux de mux 203 connected to the second interleaver 206 since the injection light is input to the second port of the first mux de mux 203 the injection light is output as odd channels and input as injection light to a light injected light source 201 1 of the odd channels the light injected light sources may include a fabry perot laser or a reflective semiconductor optical amplifier.