Optical Fiber Sensor Based on Second-Order Superstructure Fiber Bragg Grating

Toshihiro Takeshita ,Hirofumi Nogami ,Yutaka Hayashida ,Hisami Ando ,Renshi Sawada

doi:10.18494/sam.2016.1295

Abstract

Optical Fiber Sensor Based on Second-Order Superstructure Fiber Bragg Grating

Highlights

Since the first fabrication of a fiber grating by transverse holographic technology in 1989,(1) the fiber grating has been developed for various applications such as telecommunications and fiber sensor systems.[2,3,4] Optical fiber sensors are currently attracting significant interest for civil engineering applications and biosensors
According to the grating period, fiber gratings can be divided into short-period gratings and long-period gratings (LPGs)
The resonant wavelengths λLPG depend on the difference between the refractive indices of the core mode, nco, and the nth cladding mode, ncl(n), as well as the grating period ΛLBG

Summary

Introduction

Since the first fabrication of a fiber grating by transverse holographic technology in 1989,(1) the fiber grating has been developed for various applications such as telecommunications and fiber sensor systems.[2,3,4] Optical fiber sensors are currently attracting significant interest for civil engineering applications and biosensors. The sensors have the potential to be used to measure pressure and deformations in numerous environments, such as smart structures or composite materials in bridges or dams.[5,6] For these applications, different types of fiber gratings can be designed and fabricated according to the index modulation distribution and grating period design.[2] In general, a single channel fiber grating is more often used for sensing only one physical parameter by measuring the Bragg wavelength shift. ISSN 0914-4935 © MYU K.K. is introduced in regularly separated wavelength channels, resulting in a comblike reflection spectrum.[3] On the basis of the codirectionality and the counterdirectional coupling of an SFBG, a fiber sensor with a single sensing component has been used to measure multiple parameters simultaneously, such as axial strain, pressure, temperature, and curvature.[4,5,6]. We experimentally demonstrated that the refractive index (RI) sensitivity of this sensor is larger than that of the first-order SFBG

Second-Order SFBG Fabrication

Experimental Setup and Results

Conclusions