Erbium-doped fiber cascaded coreless fiber temperature and curvature sensor based on MZI

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This study presents a dual-parameter fiber-optic sensor with record-breaking sensitivity through erbium-doped fiber (EDF)-coreless fiber (CLF) cascaded interferometry. The EDF enables dual modulation, thermal expansion alters the pseudo-Fabry–Pérot (FP) cavity length (phase shift) while photothermal effects induce Mach–Zehnder interferometer (MZI) intensity changes. Temperature affects both FP and MZI, whereas curvature exclusively modulates CLF-induced MZI leakage, achieving decoupled sensing. Experimental results show record sensitivity (0.415 dB/°C for temperature, R 2 =0.996; −6.469dB/m −1 for curvature, R 2 =0.993). The all-fiber fused low-cost structure improves temperature resolution by >25% over existing intensity-modulated sensors, enabling industrial monitoring and smart infrastructure applications.