US Patent 7254325 Method and system for optical performance monitoring

In accordance with one embodiment of the present invention, a system for monitoring a performance characteristic of an intensity modulated phase shift keying optical signal includes a splitter, a first detector, and a second detector. The splitter is operable to receive an intensity modulated phase shift keying optical signal from an optical network and route at least a portion of the signal to the first detector. The first detector generates an electrical signal based on the received optical signal without demodulating the optical signal. The second detector measures a performance characteristic of the intensity modulated phase shift keying optical signal based on a signal indicative of the filtered signal.