Lossy Mode Resonance Sensors Fabricated by RF Magnetron Sputtering GZO Thin Film and D-Shaped Fibers

Abstract

We demonstrate a new refractive index (RI) and salinity sensor based on a lossy mode resonance (LMR) effect which combines fiber-optic side-polishing and radio-frequency (RF) sputtering techniques. The side-polished fiber can enhance optical fibers to generate an evanescent field in sensing applications. Gallium-doped zinc oxide (GZO) thin films produce a high attenuation lossy mode resonance effect that permits a highly sensitive refractive index and salinity fiber sensor. GZO thin film was prepared by an RF magnetron sputtering method. The thickness of the D-shaped fiber sensing device was 74.7 μm, and a GZO film thickness of 67 nm was deposited on the polished surface of the D-shaped fiber to fabricate LMR type liquid salinity sensors. The sensitivity of 3637.8 nm/RIU was achieved in the RI range of 1.333 to 1.392. To investigate the sensitivities of LMR salinity sensors, the NaCl solution salinities of 0%, 50%, 100%, 150%, 200%, and 250% were measured in this work. The experimental result shows that the sensitivity of the salinity sensor is 0.964 nm per salinity unit (SU).

Recent Advances in Lossy Mode Resonance-Based Fiber Optic Sensors: A Review

“…To enhance the performance of fiber optic LMR sensors, various geometries and configurations of optical fibers have been realized recently, such as straight core optical fibers [39,42,43,55,[65][66][67][68], tapered fibers [69][70][71][72][73][74][75], U-shaped fibers [76], D-shaped fibers [77][78][79][80][81], etc. In this section, we provided a detailed explanation of various fiber geometries and the steps involved during their fabrication processes.…”

Highly sensitive salinity and temperature measurement based on tapered-SHF MZI fiber laser structure

“…Therefore, it has been widely concerned by scholars [8]. Various fiber optic salinity sensors have been reported, such as configurations based on fiber Bragg gratings (FBGs) [9], surface plasmon resonance (SPR) effects [10], optical microfiber coupler sensor [4], as well as fs-laser direct writing [11], etched [12], polished [13] or taper fibers [14].…”

A U-Shaped Optical Fiber Temperature Sensor Coated with Electrospinning Polyvinyl Alcohol Nanofibers: Simulation and Experiment

“…These properties lend particular advantages in many harsh environments, including current applications in industrial and defense contexts. In addition to taking physical quantity measurements, many scholars in recent years have fabricated various sensor layers by using nanomaterials [ 2 ], polymer materials [ 3 ], and magnetron sputtering [ 4 ]. These diverse sensor layers are used in humidity [ 5 ], biomedicine [ 6 , 7 ], electromagnetic field [ 8 ] detection as well as in fabricating optical fiber sensors with higher sensitivities.…”