Patent ID: 7561803

Claim:
A signal interface comprising: a) a non-reciprocal device having a first port that accepts a first electrical signal and a second port that accepts a second electrical signal, the non-reciprocal device passing the second electrical signal through the first port without a phase shift and passing the first electrical signal through the second port with a 180 degrees phase shift; and b) an optical modulator having an optical input port that receives an optical signal, a first and a second electrical input port that receive the second electrical signal, a third electrical input port that receives the first electrical signal, and a fourth electrical input port that is electrically coupled to the second port of the non-reciprocal device so that it receives the phase shifted first electrical signal, the optical modulator passing the second electrical signal to the first port of the non-reciprocal device without a phase shift and modulating the first electrical signal on the optical signal and providing the modulated optical signal at an optical output port of the optical modulator.