Liquid-core low-refractive-index-contrast Bragg fiber sensor

TL;DR

This paper introduces a novel low-refractive-index-contrast hollow-core Bragg fiber sensor that detects liquid analyte refractive index changes through spectral shifts, demonstrating high sensitivity and potential for improved sensing applications.

Contribution

The study presents the design, experimental validation, and theoretical analysis of a low-contrast Bragg fiber sensor for liquid refractive index detection, highlighting its advantages over high-contrast fibers.

Findings

Achieved spectral shifts with ~1400nm/RIU sensitivity.

Demonstrated effective detection of NaCl solution concentrations.

Showed low-contrast fibers are more suitable for liquid sensing.

Abstract

We propose and experimentally demonstrate a low-refractive-index-contrast hollow-core Bragg fiber sensor for liquid analyte refractive index detection. The sensor operates using a resonant sensing principle- when the refractive index of a liquid analyte in the fiber core changes, the resonant confinement of the fiber guided mode will also change, leading to both the spectral shifts and intensity changes in fiber transmission. As a demonstration, we characterize the Bragg fiber sensor using a set of NaCl solutions with different concentrations. Strong spectral shifts are obtained with the sensor experimental sensitivity found to be ~1400nm/RIU (refractive index unit). Besides, using theoretical modeling we show that low-refractive-index-contrast Bragg fibers are more suitable for liquid-analyte sensing applications than their high-refractive-index-contrast counterparts.