Design and characteristics of refractive index sensor based on thinned and microstructure fiber Bragg grating

Abstract

A refractive index sensor based on the thinned and microstructure fiber Bragg grating (ThMs-FBG) was proposed and realized as a chemical sensing. The numerical simulation for the reflectance spectrum of the ThMs-FBG was calculated and the phase shift down-peak could be observed from the reflectance spectrum. Many factors influencing the reflectance spectrum were considered in detail for simulation, including the etched depth, length, and position. The sandwich-solution etching method was utilized to realize the microstructure of the ThMs-FBG, and the photographs of the microstructure were obtained. Experimental results demonstrated that the reflectance spectrum, phase shift down-peak wavelength, and reflected optical intensity of the ThMs-FBG all depended on the surrounding refractive index. However, only the down-peak wavelength of the ThMs-FBG changed with the surrounding temperature. Under the condition that the length and cladding diameter of the ThMs-FBG microstructure were 800 and 14 mum, respectively, and the position of the microstructure of the ThMs-FBG is in the middle of grating region, the refractive index sensitivity of the ThMs-FBG was 0.79 nm/refractive index unit with the wide range of 1.33-1.457 and a high resolution of 1.2 x 10(-3). The temperature sensitivity was 0.0103 nm/ degrees C, which was approximately equal to that of common FBG.

Near-Field Nanofluid Concentration Measurement by Rayleigh Particle Scattering Bragg Grating Evanescent Wave

“…Our previous work [36] have reported that reflectance ratio of the fiber EW sensor with Bragg grating was not changed by a little fluctuation of the surrounding temperature. The reflectance spectrum of Bragg grating kept original profile, and only red shifted or blue shifted with the change of the surrounding temperature, thus, the reflectance ratio of the fiber sensor with Bragg grating was not attenuated.…”

“…[36] Light emitted from Amplified Spontaneous Emission (ASE) routed the circulator to arrive at Bragg grating. The reflected light from the Bragg grating was split into two paths using the coupler (50:50) and interrogated by DWDM and Power meter to obtain Bragg wavelength shift and reflected optical power attenuation.…”

Recent developments in microstructured fiber Bragg grating refractive index sensors

“…These conditions mean that the reflectance spectrum profile of the double peaks remains almost unaffected by the disturbance of the surrounding temperature but simply shifts. However, once the SRI increases to be larger than the cladding index, the intensity of double peaks decreases dramatically [36].…”

Side polished fiber Bragg grating sensor for simultaneous measurement of refractive index and temperature

“…Recently, optical fiber is widely used in the field of sensors due to its advantages, such as portability, free from electromagnetic interference, low cost, rapid response. Surface plasmon resonance wave optical fiber endecho and fiber grating [1][2][3][4][5] are typical optical fiber sensors to measure refractive index.…”

“…Etching method was used to remove the cladding of FBG' grating area and then various sensors based on refractive index were reported [1,2,3,11,12]. In this paper, simultaneous measurement of refractive index and temperature with a side polished fiber Bragg grating (SPFBG) is proposed and demonstrated experimentally to measure refractive index of liquid and temperature simultaneously.…”