2.7μm surface plasmon resonance fiber optic sensors

In this work, we demonstrated a mid-infrared surface plasmon resonance (SPR) fiber optic sensor utilizing a D-shaped multimode silica optical fiber coated with a 105 nm indium tin oxide (ITO) layer. The sensor presented resonance at approximately 2700 nm with a refractive index sensitivity of 1055.33 nm/RIU Compared to that of visible light, midinfrared wavelengths enable deeper evanescent field penetration, allowing greater probing depths for biological samples. Moreover, the overlap of the mid-infrared spectrum with the molecular fingerprint region offers substantial potential for advanced gas detection applications.