Simultaneous Multi-Point Refractive Index Sensing Using FIB-Fabricated D-Shaped Optical Fiber Sensors Integrated with OTDR

This dataset presents experimental results from simultaneous refractive index measurements using two D-shaped multimode optical fiber sensors fabricated via Focused Ion Beam (FIB) milling and interrogated using Optical Time Domain Reflectometry (OTDR). The sensors were connected in series and exposed to glycol solutions of varying refractive indices. The measurements were conducted at 850 nm and 1300 nm wavelengths using an EXFO MaxTester 720C OTDR. Each sensor consisted of a precisely milled slit region enabling light interaction with the external medium. The data include the normalized reflected signal intensity as a function of refractive index for both sensors. These results demonstrate the feasibility of multi-point sensing in a single fiber path using standard OTDR instrumentation. The dataset may support further research on distributed refractive index sensing, multi-sensor configuration optimization, and sensitivity analysis of FIB-structured fiber optic sensors.