Specialty optical fibers and 2D materials for sensitivity enhancement of fiber optic SPR sensors: A review

In this paper, a review of recent studies on the optical fiber-based surface plasmon resonance (SPR) sensor and the sensitivity improvement based on specialty optical fibers and two-dimensional (2D) materials is given. The configurations and working principles of various SPR excitation methods are introduced. Several types of specialty optical fibers, including polymer fiber, multi-core fiber, hollow fiber, photonic crystal fiber, are discussed in detail with enhanced sensing configurations. Furthermore, some hybrid configurations using 2D materials like graphene, transition metal dichalcogenides, and black phosphorus are reviewed in terms of properties, sensing structures, and application fields. The review aims to provide an overview of the latest achievements in optical fiber-based SPR sensing technology, with emphasis on research towards sensitivity improvement.