| 摘要 |
A first coupler, a second coupler, FBG, a third coupler, BA, and a fourth coupler are connected in series and inserted between an input-side optical fiber and an output-side optical fiber. An input wavelength multiplexed signal is branched by a branching filter connected to the second coupler into individual wavelengths, and, based on the output of the branching filter, the number of wavelengths in branch optical signal is computed in a branch optical signal wavelength number computation section. On the other hand, the number of wavelengths in insertion optical signal is computed in an insertion optical signal wavelength number computation section based on insertion optical signal, and the number of wavelengths in input optical signal is computed based on an SV signal branched from the first coupler. The number of wavelengths in output optical signal is computed in an output optical signal wavelength number computation section based on the above numbers of wavelengths in the above three optical signals and is multiplexed into an output optical signal in the fourth coupler. By virtue of the above construction, an OADM system can be provided wherein, even when the number of multiplexed wavelengths is increased, the necessity of providing monitors for respective wavelengths of an input (output) wavelength multiplexed signal can be eliminated and, thus, a combination of the prevention of an increase in cost with an improvement in reliability can be realized.
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