Simultaneous measurement of bending and temperature based on a single sampled chirped fiber Bragg grating embedded on a flexible cantilever beam

Abstract

We propose and experimentally demonstrate a simple and practical scheme for simultaneous measurement of bending and temperature based on a single sampled chirped fiber Bragg grating with multiple resonant peaks, which is embedded on a flexible cantilever beam. The wavelength spacing of the grating can be changed by adjusting the bending curvature change, since the compressive strain gradient induced by the bending of the cantilever beam changes the chirp ratio of the fiber grating. However, the wavelength spacing of the fiber grating is not changed by the temperature variation; the multiple resonant wavelengths are only shifted into the longer wavelength because of the positive thermal-expansion and thermo-optic coefficients of the fiber grating. Consequently, the proposed scheme allows for discrimination between two effects of bending and temperature.

Mach–Zehnder Photonic Crystal Interferometer in Cavity Ring-Down Loop for Curvature Measurement

“…If temperature variation of 0.1 C can be maintained in normal working condition, this gives a curvature change of 1.094 m . Comparison is done against 5 cm long chirped FBG curvature sensor which has minimum detectable curvature of 38 m [8]. It is 7 times larger than the one displayed in the CRD PCF curvature sensor, which implies higher curvature sensitivity in our proposed technique.…”

Simultaneous Measurement of External Refractive Index and Temperature by Using a Side-polished Fiber Bragg Grating with a Polymer Overlay

“…광섬유 격자 기반의 광 센서 소자들은 외부의 굴절률, 온 도, 인장력, 하중, 구부림, 진동, 압력 등 다양한 물리량에 높 은 민감성을 가지고 있어 센서 응용 분야에 상당한 관심을 받아왔다 [1][2][3] . 광섬유 격자들은 여러 물리량들로부터 복합적 으로 영향을 받기 때문에, 광섬유 격자들의 파장특성을 이용 하여 두 개 이상의 물리적 변수를 동시에 측정하는 다수의 방법들이 소개되었다 [4][5][6] .…”

Spectra power and bandwidth of fiber Bragg grating under influence of gradient strain

“…Most of the researches focus on the wavelength sensing technology and theory, but when the inhomogeneous field applying on the FBG, such as the gradient stain and gradient temperature, acts on the grating range of the FBG, which can lead to the FBG chirping, and the reflective spectrum shows new features, such as reflective power and reflective bandwidth [6][7][8][9][10]. It has many methods to form inhomogeneous refractive-index modulation, such as designing the grating structure [11,12], introducing a strain gradient by designing an especial fabrication structure [13,14], and etching the FBG [15].…”