High sensitivity refractive index sensor in long-range surface plasmon resonance based on side polished optical fiber

• Main Authors: Zakaria, Rozalina, Zainuddin, NurAina'a Mardhiah, Fahri, Muhammad Aiman Saufi Ahmad, Thirunavakkarasu, Punithavathi M., Patel, Shobhit K., Harun, Sulaiman Wadi
• Format: Article
• Published: Elsevier 2021
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.um.edu.my/28355/

A side-polished single mode optical fiber based on conventional long-range surface plasmon resonance (cLRSPR) sensor and symmetrical long-range surface plasmon resonance (sLRSPR) sensor was proposed and experimentally demonstrated. The proposed structure of cLRSPR is composed of optical fiber/dielectric buffer layer (DBL)/Ag film while for sLRSPR is consisted of optical fiber/DBL/Ag film/DBL. Magnesium fluoride, MgF2 with 50 nm thickness is used as DBL layer that lies beneath of Ag film in cLRSPR and covering both sides of Ag film in sLRSPR. 40 nm thickness of Ag layer is used with 5 mm length of sensing region. The result suggested that the sensing performance in terms of sensitivity of the cLRSPR sensor was better compared to sLRSPR and previous works of conventional surface plasmon resonance (cSPR) as it achieves as high as 2812.5 nm/RIU at 0.01 interval of refractive index with refractive index (RI) range of 1.33-1.34. The larger the sensitivity value indicates the better the performance of the SPR sensor. This design is expected to play an important role on chemical sensing and biological sensing as it displays higher penetration depth.