Electric signal sensor using an electrooptic coherence modulator

This work presents a novel system for sensing electric signals using an electrooptic modulator and optical coherence modulation. The system consists of an integrated optics coherence modulator acting as electric signal sensor in the frequency range up to 900 MHz. The main features of coherence-modulated transmissions include the need of using broad-band optical sources and lithium niobate electrooptic retarders. When low-coherence optical sources are used, the retarders introduce optical delays which are modulated by detected electric signals. The optical delays carry electric signals and are transmitted in the optical channel to a receiver. In this case, a scanning Michelson interferometer is used as an optical receiver, which measures the autocorrelation of light. The sensed electric signal is obtained when the interferometer is matched with optical delays on the detecting devices. Coherence-modulated systems have been studied for the last few years as new potential high-speed optical links useful for local area networks, point-to-point, and bidirectional transmissions.