Nano-Graphene Based Chemical Sensing Applications

Abstract

This work presents the development of optical fiber-based sensors utilizing multi-mode optical fibers. Two optical fibers were chemically tapered using hydrofluoric acid (HF) with different tapering durations 40 and 60 minutes, and each fiber was coated with a nanolayer of graphene, with different thicknesses depending on the tapering time. A noticeable red shift was revealed in the resonance wavelength as the ethanol concentration increased, clearly demonstrating a relationship between the refractive index of the external environment and the sensor’s optical performance. The sensor with 40 min tapering exhibited a sensitivity of 16.451 µm/RIU, while the 60 min tapered sensor showed slightly higher sensitivity of 16.666 µm/RIU. Additionally, the 60 min sensor demonstrated a superior figure of merit (FOM) of 14.28 compared to 5.06 for the 40 min sensor. These findings confirm that graphene-coated tapered multimode optical fibers are promising candidates for highly sensitive chemical sensing applications.