Highly Sensitive Optical Fiber Plasmonic Sensors by Integrating Hydrogen Doped Molybdenum Oxide

We propose a sensitivity enhanced surface plasmon resonance (SPR) sensor with two-dimensional (2D) hydrogen doped molybdenum oxide (HMO) nanodisks integrated onto an Au-coated optical fiber. Through ionic doping, the molybdenum oxide exhibits tunable plasmonic resonance in the visible to the near-infrared wavelength region, which in turn enhances the light-matter interaction. A resonant peak redshift of the Au-coated optical fiber is observed due to the deposition of the HMO. Within a certain thickness, the refractive index (RI) sensitivity has a positive correlation to the ion doping concentration of HMO, with the average sensitivity showing an enhancement of 84.5%, and the highest sensitivity to be 4566 nm/RIU. Optimized modification of HMO with four cycles is experimentally verified with a sensitivity of 2178 nm/RIU (1.334-1.362) and a figure of merit (FOM) of 29.73 RIU
⁻¹
. This optical fiber SPR sensor can be readily expanded to the application fields like clinical diagnosis and environmental monitoring.