Single-mode all-fiber structured modal interference for temperature and refractive index sensing

Abstract

A new type of optical fiber sensor based on an asymmetric structured microfiber modal interferometer is proposed and demonstrated. The sensor head is simply made of singlemode fiber using the electrical arc discharge technique. Owing to the reflection spectrum dips formed by the interference between the cladding modes and the core mode, measurements of temperature and the refractive index (RI) can be obtained by monitoring the wavelength shifts of the interference spectrum. Experiments show that the sensor exhibits a good response to temperature and the ambient RI variation, with maximum sensitivities of 0.079 nm °C-1 and -49.957 nm/RIU, respectively. The merits of its cost-effective and simple fabrication makes this sensor a promising device for sensing applications.

An All-Fiber Fabry–Pérot Sensor for Emulsion Concentration Measurements

“…The open path FPI’s sensitivity to residue is, thus, generally decreased by increasing the length of the microcell optical path involved in the sensor design. In contrast, sensors that exploit evanescent field interactions (most FBG RI sensors [ 12 , 13 , 14 ], LPFG sensors [ 15 , 16 , 17 ], modal interference sensors [ 18 , 19 , 20 ], etc.) exhibit substantially higher sensitivity to the formation of deposits and residues, as even a very thin formation of the undesired residue film on the sensor surface results in a substantial change in the average RI of the volume that is involved in the measurement of the RI.…”

Enhanced Mach-Zehnder interferometer multimode–single-mode–multimode fiber optic refractive index sensor based on surface plasmon resonance

“…MZI configurations are superior and more reliable owing to their simplicity, high sensitivity, and structural diversity. The main structures in the category of MZI configuration-based FOSs are based on: a sandwiched thin core (TC)-photonic crystal (PC) fiber [5], a TC-PC-TC fiber connected between two single-mode fibers (SMFs) [6], an asymmetric microfiber [7], an inline multimode-single-mode-multimode (MSM) [8], a single-mode-multimode-singlemode(SMS) fiber in which the first end of the multimode fiber (MMF) is tapered [9], an embedded four-core fiber between two SMFs [10], and an in-line MMF-etched multicore fiber-MMF [11]. The propagating light is not thoroughly confined in these sensors, and the evanescent waves (EWs) penetrate the surrounding media.…”

Micro-air cavity incorporated tapered-tip photonic crystal fiber based compact refractometer

“…In addition, several approaches have been made in order to improve the compactness, response and strength of evanescent field in reflection based sensing probes. For example, a tapered single mode fiber (SMF) based interferometer has been found to have a sensitivity of −49.96 nm RIU −1 [5]. Further, chemically etched tapered fiber, microfiber based half coupler, stapered fiber have also been developed for RI sensing [6][7][8][9].…”