Enhanced refractive index sensor using a combination of a long period fiber grating and a small core singlemode fiber structure

Abstract

Enhanced refractive index sensor using a combination of a long period fiber grating and a small core singlemode fiber structure. Measurement Science and Technology, 24 (2013) Abstract An enhanced refractive index (RI) sensor based on a combination of a long period fiber grating (LPG) and a small core singlemode fiber (SCSMF) structure is proposed and developed. Since the LPG and SCSMF transmission spectra experience a blue and a red shift respectively as the surrounding RI (SRI) increases, the sensitivity is improved by measuring the separation between the resonant wavelengths of the LPG and SCSMF structures. Experimental results show that the sensor has a sensitivity of 1028 nm/SRI unit in the SRI range from 1.422 to 1.429, which is higher than individual sensitivities of either structure alone used in the experiment. Experimental results agree well with simulation results.

Singlemode-Multimode-Singlemode Fiber Structures for Sensing Applications—A Review

“…(Fig. 8(a)) to excite both core and cladding Bragg wavelengths for simultaneous measurement of RI and temperature [134]; The MMF can also be replaced by an NCF [135][136] or the FBG could be replaced by an LPG for multiple parameter measurement with improved sensitivity [137]; an FBG inscribed within a centre section MMF (Fig. 8(b)) is also possible and has also been studied for simultaneous measurement of temperature and other parameters such as strain or bending [138][139][140].…”

Optical fiber refractive index sensor with low detection limit and large dynamic range using a hybrid fiber interferometer

“…In order to simplify preparation procedures, achieve high sensitivity, and avoid the high cost and photo-bleaching of fluorescent tags, optical fiber RI-based biosensors have been studied extensively [15,16] as the optical fiber platform offers a number of advantages, namely small size, bio-compatibility, immunity to electromagnetic interference, and the potential for remote operation. There are numerous optical fiber sensing mechanisms that have been demonstrated for use as RI sensors, with examples including Mach-Zehnder (MZ) interferometers [12,[17][18][19][20][21], Fabry-Perot interferometers [22,23], surface plasmon resonance [24,25], fiber Bragg-gratings [26][27][28], longperiod fiber gratings [29][30][31], and Sagnac (SG) interferometers [13,32]. There are typically trade-offs in performance depending on the mechanism used.…”