Ultra-Sensitive Intensity Modulated Strain Sensor by Tapered Thin-Core Fiber Based Modal Interferometer

Chuanxu Liu,Hui Zhang,Dexue Sun,Lingling Ran,Jiuru Yang

doi:10.3390/photonics8090372

Chuanxu Liu, Hui Zhang + Show 3 more

Open Access

https://doi.org/10.3390/photonics8090372

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Journal: Photonics	Publication Date: Sep 3, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Heilongjiang University, GoerTek (China)

Abstract

In this paper, to enhance practicality, a novel tapered thin-core fiber (t-TCF) based modal interferometer is proposed and demonstrated experimentally. The light field distribution of t-TCF structure is investigated by a beam propagation method, and the quantitative relationship is gained between light intensity loss and waist diameter. Under ~30 μm waist diameter, multiple t-TCF based sensor heads are fabricated by arc-discharged splicing and taper techniques, and comprehensive tests are performed with respects to axial strain and temperature. The experimental results show that, with near-zero wavelength shift, obvious intensity strain response is exhibited and negative-proportional to the reduced length of TCF. Thus, the maximum sensitivity reaches 0.119 dB/με when the TCF length is equal to 15 mm, and a sub-micro-strain detection resolution (about 0.084 με) is obtained. Besides, owing to the flat red-shifted temperature response, the calculated cross-sensitivity of our sensor is compressed within 0.32 με/°C, which is promising for high precision strain related engineering applications.

Highlights

Fiber-optic strain sensors have the advantages of a compact structure, light weight and anti-electromagnetic interference, which has been widely used in high precision measurement, health-monitoring of building structures and aerospace engineering [1,2,3,4,5]
Strain sensors based on fiber Bragg grating (FBG) [6,7], long-period fiber grating (LPFG) [8,9], polymer optical fiber (POF) [10,11,12] and photonic crystal fiber (PCF) [13,14] are easy to fabricate, but the sensitivity is usually only ~1 pm/με
Under a suitable waist diameter, we experimentally prove that the energy loss of an evanescent wave field is very sensitive to the variation of the waist diameter caused by the increased or decreased axial strain

Summary

Introduction

Fiber-optic strain sensors have the advantages of a compact structure, light weight and anti-electromagnetic interference, which has been widely used in high precision measurement, health-monitoring of building structures and aerospace engineering [1,2,3,4,5]. Strain sensors based on fiber Bragg grating (FBG) [6,7], long-period fiber grating (LPFG) [8,9], polymer optical fiber (POF) [10,11,12] and photonic crystal fiber (PCF) [13,14] are easy to fabricate, but the sensitivity is usually only ~1 pm/με. The modal interference based fiber optic strain sensors, derived from the excitation of higher-order cladding modes, has received much attention [15,16,17]. PCF-based modal interferometers are proposed, and a 2–3 pm/με strain sensitivity is reported with ultralow temperature cross-talk [18,19,20]. Yin respectively fabricated the bubble based micro-cavity interferometers through precise arc-discharge control, and the strain sensitivities were further increased to more than. Compared with wavelength sensitive structures, the intensity demodulation schemes can greatly improve the practicability and portability of sensors without an expensive and heavy high-precision

Methods

Results

Conclusion