Plasmonic Sensor System Embedded with Orthogonal Mode Couplers for Simultaneous Monitoring of Temperature and Refractive Index

Abstract

The significance of plasmonic sensors lies in their ability to enhance sensitivity and precision in detecting minute variations in the refractive index of surrounding media. In this work, a novel plasmonic sensor design utilizing a metal-insulator-metal (MIM) waveguide and two circular cavities is presented, specifically tailored for refractive index and temperature sensing applications. Each cavity serves as an individual and autonomous sensing unit. Tailored for temperature sensing, a designated cavity is filled with polydimethylsiloxanes (PDMS), while a separate cavity is exclusively allocated for biosensing and contains a liquid with distinct refractive indices. This dual-cavity system allows for precise and specialized sensing functionalities, ensuring accurate measurements and diverse applications. Furthermore, this work integrates orthogonal mode couplers into the plasmonic device, providing an essential capability to seamlessly transform the dielectric mode into a plasmonic mode and vice versa. The device exhibits a refractive index sensitivity of 737.71 nm/RIU and a temperature sensitivity of − 0.336 nm/°C. Additionally, its Q-factor is determined at 20.5 for the refractive index sensing module and 16.5 for the temperature sensing module.