Backward Brillouin three-parameter sensing simulation based on multicore optical fibers

Conventional distributed Brillouin optical fiber sensors, whether theoretically modeled or experimentally implemented, provide simultaneous access to only two physical parameters at most, typically limited to either curvature or temperature-strain. Here, we theoretically study a three-parameter sensor based on backward Brillouin scattering and develop a sensing error assessment model in a multicore fiber (MCF) configuration with one inner core, three outer cores, and a two-step refractive index profile. This sensor enables discriminative recognition of temperature, strain and curvature parameters through combining the spatial division multiplexing (SDM) with acoustic-mode division multiplexing (AMDM) in both inner and outer cores. We establish a 3D matrix for error-quantified tri-parameter recovering. The maximum errors of temperature, strain, and curvature radius, in theory, are 1.7410°C, 44.3315 µε, and 2.4727 × 10^-3 m, respectively. This theoretical work potentially offers a crucial reference for Brillouin distributed sensing from traditional dual-parameter to next-generation three-parameter sensing systems.