METHOD AND DEVICE FOR REJECTING NOISE

摘要

PROBLEM TO BE SOLVED: To reject an AM modulation component caused by a Raman effect of an optical analog signal.

SOLUTION: The optical analog signal is made incident on an optical multiplexer 24 through a WDM (wavelength division multiplexing) optical coupler 20. A laser beam for reducing an AM modulation component from a laser diode (LD) 26 is made incident on the optical multiplexer 24. A photoelectric converter 30 converts output light of the multiplexer 24 into an electrical signal. A separator 32, electrical filters 34-1 to n and power meters 36-1 to n measure the power of a prescribed frequency component. Comparison circuits 38-1 to n output differences between measured results of the power meters 36-1 to n and thresholds Ref1 to Refn. Respective amplitude/phase/frequency controllers 42-1 to n sweep amplitude and phases of generators 44-1 to n of central frequencies f1 to fn so as to make an output difference value of a corresponding comparator 38-1 to n small. A multiplexer 46 multiplexes outputs of the generators 44-1 to n and applies the outputs to a driving circuit 48 of the LD 26.

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