Lin Wenwei, Bang Ole, Woyessa Getinet
Opt Express. 2025 Jan 27;33(2):1962-1968. doi: 10.1364/OE.547355.
We propose and experimentally demonstrate what we believe to be the first mid-infrared surface plasmon resonance (SPR) fiber optic sensor using a D-shaped multimode silica optical fiber coated with a 105 nm indium tin oxide (ITO) layer. The sensor shows resonance around 2700 nm, with a refractive index sensitivity of 1065.70 nm per refractive index unit (nm/RIU) for refractive indices ranging from 1.33 to 1.42. Since the evanescent wave outside the fiber decays within approximately 1/3 of its wavelength, the use of mid-infrared wavelengths can significantly increase the probing depth of SPR sensors compared to what is obtained when using visible light. This would allow SPR sensors to probe a larger volume, potentially improving sensitivity and signal-to-noise ratio. In addition, the mid-infrared region aligns with the molecular fingerprint region, which can unlock the potential for gas detection.
我们提出并通过实验证明了我们认为的首个使用涂覆有105纳米铟锡氧化物（ITO）层的D形多模石英光纤的中红外表面等离子体共振（SPR）光纤传感器。该传感器在2700纳米左右显示出共振，对于折射率范围从1.33到1.42的情况，其折射率灵敏度为每折射率单位1065.70纳米（nm/RIU）。由于光纤外部的倏逝波在其波长的大约1/3范围内衰减，与使用可见光时相比，使用中红外波长可以显著增加SPR传感器的探测深度。这将使SPR传感器能够探测更大的体积，有可能提高灵敏度和信噪比。此外，中红外区域与分子指纹区域相匹配，这可以开启气体检测的潜力。
