Giant sensitivity of optical fiber sensors by means of lossy mode resonance

Here we show an optical refractometer with a giant sensitivity of 304,360 nm per refractive index unit (nm/RIU). This sensitivity corresponds to a resolution of 3.28 × 10−9 RIU if a standard optical spectrum analyzer with a resolution of 1 pm is used. This record sensitivity is obtained by means of a lossy mode resonance (LMR) optical fiber sensor in a surrounding media with refractive index around 1.45. This achievement implies that the utilization of the LMR phenomenon opens the door to devices and systems that can beat, in terms of sensitivity, those used currently in real-time biomolecular analysis such as surface plasmon resonance (SPR) devices.