Patent ID: 7609979
Filing Date: 2009-10-27
Classification: H04B

Abstract:
1. A coherent optical detection system receiving an incoming optical signal in a fiber optics network, said system comprising: two local oscillators, each local oscillator emitting light; an optical mixing hybrid for generating at least four optical waves similar to the incoming optical signal and two optical waves similar to light from each of the local oscillators, said optical mixing hybrid combining the optical waves similar to the incoming optical signal and the optical waves similar to the local oscillator light into at least four outputs and wherein said local oscillators do not have to be phase locked to the incoming optical signal; four photodetectors communicating with the optical mixing hybrid, wherein said four photodetectors receive optical signals from four of the at least four outputs; four A/D converters to receive electrical signals from the four photodetectors, said four A/D converters digitizing the received electrical signals; and a digital signal processor for performing computations on digital values from the four A/D converters to obtain information carried by the incoming optical signal without limitation to the state of polarization of the incoming optical signal.