A Fiber Ring Laser Sensor with a Side Polished Evanescent Enhanced Fiber for Highly Sensitive Temperature Measurement.

Weihao Lin,Mang I Vai,Liyang Shao,Yibin Liu

doi:10.3390/mi12050586

Weihao Lin, Mang I Vai + Show 2 more

Open Access

https://doi.org/10.3390/mi12050586

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Abstract

We demonstrate a highly sensitive and practical fiber-based temperature sensor system. The sensor is constructed based on a fiber ring laser (FRL) as well as a side-polished fiber filled with isopropanol. The laser cavity of the sensing part fiber is polished by the wheel fiber polishing system with residual thickness (RT) is selected to detect the temperature in the FRL. Thanks to the high thermo-optic coefficient of isopropanol, the sensitivity of the proposed temperature sensor could be effectively improved by filling isopropanol in the cost-less side polished single mode fiber. Refractive index (RI) of isopropanol changes with the surrounding temperature variation allowing high-sensitivity temperature sensing. Experimental results demonstrate that the side polished fiber can efficiently excite high-order cladding modes which enhance the modular interference increase the interaction between the evanescent wave and the isopropanol. Besides, the results show that the sensitivity can be as high as 2 nm/°C in the temperature range of 25–35 °C.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Value of isopropanol changes with the temperature [21], the effective Refractive index (RI) difference beis infiltrated into the side polished fiber, the core mode and the isopropanol mode vary tween the core mode and the cavity mode will increase with the increment of temperature
A compact side-polished fiber temperature sensor filled with isopropanol is developed in fiber ring laser (FRL)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. There are various optical fiber structures designed for temperature measurement [11,12,13,14,15]. Jian et al proposed a novel fiber optic magnetic field sensor based on D-shaped fiber optic modal interferometer. Wang el al, demonstrated a surface plasmon resonance (SPR) of a side-polished single mode fiber for temperature sensing thanks to the high thermo-optic and thermal expansion coefficient of the adhesive [26]. To address the aforementioned challenges and difficulties, we have designed and fabricated a new sensing system to measure the temperature of the ambient environment by using a side polished evanescent enhanced fiber structure filled with isopropanol in a fiber ring laser system. The stability of power fluctuation and wavelength shift are tested and analyzed

Working Principle

Discussion

Conclusions