Micro-displacement sensors based on plastic photonic bandgap Bragg fibers

TL;DR

This paper presents a novel amplitude-based micro-displacement sensor using plastic photonic bandgap Bragg fibers, demonstrating high sensitivity and a detection limit below 5 micrometers, outperforming regular multimode fiber sensors.

Contribution

The work introduces a new displacement sensor leveraging Bragg fiber's mode stripping capability, enhancing sensitivity over traditional multimode fiber sensors.

Findings

Detection limit below 5 micrometers.

Bragg fiber sensor shows higher sensitivity to bending.

Mode stripper enhances sensor performance.

Abstract

We demonstrate an amplitude-based micro-displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a regular multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to presence of mode stripper in the form of the multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be smaller than 5 um for displacement sensing.