Investigation of a Bragg Grating-Based Fabry–Perot Structure Inscribed Using Femtosecond Laser Micromachining in an Adiabatic Fiber Taper

Applied Sciences

Varghese Paulose¹  Jianzhong Hao¹  PerryPing Shum²  Aayush Madan²  StephanieHui Kit Yap²  Wonkeun Chang² 

[1] Institute for Infocomm Research, Agency for Science, Technology and Research, Singapore 138632, Singapore;School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore;

关键词: fabry–perot;    microfiber sensor structure;    femtosecond laser micromachining;    direct writing;    point-by-point fabrication;    harsh environment fiber sensor;    sensor for structural health monitoring;   

DOI  :  10.3390/app10031069

来源: DOAJ

【 摘 要 】

This paper presents the fabrication of a fiber Bragg grating (FBG)-based Fabry−Perot (FP) structure (7 mm total length) in an adiabatic fiber taper, investigates its strain and temperature characteristics, and compares the sensing characteristics with a standard polyimide coated FBG sensor. Firstly, a simulation of the said structure is presented, followed by the fabrication of an adiabatic fiber taper having the outer diameter reduced to 70 $\mathsf{\mu }$ m (core diameter to 4.7 $\mathsf{\mu }$ m). Next, the sensing structure, composed of two identical uniform FBG spaced apart by a small gap, is directly inscribed point-by-point using infrared femtosecond laser (fs-laser) micromachining. Lastly, the strain and temperature behavior for a range up to 3400 $\mathsf{\mu }\mathsf{\epsilon }$ and 225 ${}^{°}$ C, respectively, are investigated for the fabricated sensor and the FBG, and compared. The fabricated sensor attains a higher strain sensitivity (2.32 pm/ $\mathsf{\mu }\mathsf{\epsilon }$ ) than the FBG (0.73 pm/ $\mathsf{\mu }\mathsf{\epsilon }$ ), while both the sensors experience similar sensitivity to temperature (8.85 pm/ ${}^{°}$ C). The potential applications of such sensors include continuous health monitoring where precise strain detection is required.

【 授权许可】

Unknown