| 摘要 |
An optical power monitor for an optical signal having a signal spectrum superimposed on a noise spectrum. Typically, the optical power monitor includes an optical coupler, first and second optical band-pass filters, first and second photodetectors, and an operating unit. The optical coupler branches the optical signal into first and second beams. The first optical band-pass filter has a first pass band including the signal spectrum, and the first beam is supplied to the first optical band-pass filter. The second optical band-pass filter has a second pass band including the signal spectrum and narrower than the first pass band, and the second beam is supplied to the second optical band-pass filter. The first photodetector receives the first beam passed through the first optical band-pass filter, and the second photodetector receives the second beam passed through the second optical band-pass filter. The operating unit calculates the power of the optical signal according to output signals from the first and second photodetectors. Since the first and second optical band-pass filters have different pass bands, the power of the optical signal relating to the signal spectrum can be precisely monitored with no effects of the noise spectrum.
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