Sensitivity-enhanced, common-mode-compensated Mach-Zehnder fiber-optic sensor circuit with electro-optic feedback

A Mach-Zehnder fiber-optic sensor circuit incorporating an optical compensation circuit to reduce errors from common-mode perturbations and electro-optic feedback to enhance measurand sensitivity is proposed and demonstrated. Experimental results show that the phase bias and the feedback constant can be adjusted to yield an operating region with negligible sensitivity to common-mode perturbations and a measurand sensitivity an order of magnitude above that expected from an equivalent conventional Mach-Zehnder sensor, in good agreement with theory.