Patent ID: 7265849

Claim:
A system for determining a spectral content of an optical signal, comprising: an optical hybrid for combining said optical signal and an optical local oscillator signal to generate phase-diverse components; a plurality of photodetectors with each photodetector illuminated by a respective one of said phase-diverse components thereby mixing said optical signal and said optical local oscillator; a plurality of bandpass filters for bandpass filtering signals from said plurality of photodetectors, wherein said bandpass filters generate filtered signals to coincide with a low-intensity noise region of said optical signal; a plurality of mixers for mixing said filtered signals from said plurality of bandpass filters with an electrical local oscillator signal; and a signal processing module that determines said spectral content utilizing signals from said plurality of mixers; wherein said photodetectors are coupled in a serial arrangement and each of said bandpass filters is coupled to a respective node between two respective photodetectors of said plurality of photodetectors.