Wideband efficiency improvement of fiber optic systems by carrier subtraction

Abstract
Carrier subtraction from a weakly modulated optical signal is proposed, analyzed, and demonstrated to improve fiber-optic system efficiency. For constant photodetector current, an amount of carrier suppression results in an equal amount of RF gain. Improvement of 9-13 dB in link loss from 1 to 25 GHz is measured using a Fabry-Perot filter operating in the reflection mode. Measured induced harmonic distortion agrees with predicted values.