Noise-like pulses in fiber optic resonator with modal interferometer applied to temperature-stable curvature sensing

Abstract

Sensor technology development aims to achieve high detection sensitivity in challenging environments, such as elevated temperatures. Although fiber optic resonators offer high sensing accuracy, their real-world applications are limited owing to high cost and complexity of advanced optical systems. Noise-like pulses (NLPs) in mode-locked fiber lasers enhance sensitivity by improving the signal-to-noise ratio, thereby allowing weak signal detection. This study investigated the interactions between a fiber optic resonator and NLPs generated through passive mode-locking for curvature sensing applications. Herein, a fiber ring resonator incorporating a modal interferometer and a laser source featuring stable temporal and spectral characteristics were used for temperature tests, where the interferometer was heated, and changes in the output pulses were observed. The results revealed that the resonator’s output pulse widths and amplitudes changed considerably with temperature increases from 25 to 100 °C. Curvature sensing tests revealed a secondary pulse train comprising three pluses with widths of 56.4–29.0 ns and amplitudes of 153–29.9 mV. Analysis of the time response of these output pulses provided insights into the sensor’s behavior under various curvature conditions. For curvature variations in the range of 0–1.1469 m⁻¹, the sensitivity of the output pulse of the combined resonator and interferometer system was in the range of − 4.06 to − 48.98 mV/m⁻¹.This study introduced a novel method for enhancing sensor sensitivity, stability, and cost-effectiveness over conventional techniques. The proposed device is highly promising for use in various applications, with the NLPs considerably enhancing the performance of the fiber optic sensor in dynamic environments.