Simultaneous measurement of refractive index and flow rate using graphene-coated optofluidic anti-resonant reflecting guidance

An anti-resonant reflecting guidance coated with a few layers of graphene has been proposed and experimentally demonstrated for the simultaneous measurement of the refractive index and liquid flow rate. A few layers of graphene were coated on the surface of a hollow core photonic crystal fibre. The refractive index and liquid flow rate can be detected by using the resonant condition of the Fabry–Perot resonator and the effective refractive index of the graphene layers heated by a visible laser beam, which are interrogated through the wavelength shift and visibility of the lossy dip in the transmission spectrum. The experimental results show that the sensitivity of up to 1328 nm/RIU and −2.99 dB/(µL/s) are achieved for the refractive index and flow rate measurement in the refractive index range from 1.345 to 1.363 RIU, respectively. The proposed sensor appears to have potential applications for precise measurement in chemistry, medicine, and biology.