High refractive index sensing based on single leaky mode attenuation

We propose a refractive index (RI) Sensing to measure surrounding RI higher than that of the silica fiber. It is realized by detecting the propagating attenuation of the fundamental leaky mode in a guided-mode–leaky-mode–guided-mode (GLG) fiber structure. By single-wavelength power monitoring with a resolution of 0.01 dB, an average sensitivity of 2.1×10−5 for the RI range from 1.465 to 1.495 is demonstrated by simulations, which is about 3 times higher than that obtained previously by using leaky mode interference in a similar structure. Our experimental results agree well with the theoretical analysis.