Additive-Noise Suppression in Interferometric Fiber-Optic Sensing Using an Intrinsic Full-Link Noninterfering Pulse

Abstract

Additive-noise suppression in interferometric fiber-optic sensing often relies on auxiliary reference optics or computationally intensive back-end processing. Here, we present an intrinsic pulse-domain scheme that turns noninterfering return pulses generated by the sensing array, normally discarded during demodulation, into intrinsic noise references. Based on the extent to which their propagation paths overlap that of the sensing interference pulse (SIP), the leading and trailing return pulses are designated the partial-link noninterfering pulse (PLNP) and the full-link noninterfering pulse (FLNP), respectively. A link-resolved additive-noise model is derived, and PLNP preprocessing, FLNP preprocessing, and direct dual-SIP differencing are evaluated theoretically and experimentally. FLNP preprocessing lowers the original SIP noise floor by 4.54 dB, consistent with the closer propagation-path match between the FLNP and the SIP. In a push-pull fiber Bragg grating (FBG) accelerometer, applying FLNP preprocessing before scaling-compensated phase-domain subtraction lowers the synthesized output noise floor by 3.40 dB relative to the same processing chain without preprocessing. These results establish intrinsic return-pulse referencing as a hardware-efficient design strategy for additive-noise suppression in interferometric fiber-optic sensing.