We propose a graphene-based photonic crystal fiber (PCF) sensor based on surface plasmon resonance. Graphene helps in prevention of oxidation of the silver layer used as a plasmonic active metal. The birefringent nature of the structure allows one component of the core guided mode to be more sensitive. Further, this structure does not need filling of the voids. The structural parameter of PCF and metal thickness has been optimized. The proposed sensor shows high amplitude sensitivity of 860 RIU ^-1 and has a resolution as high as 4×10 ^-5 RIU. This reported performance is higher than bimetallic (gold on silver) configuration.

We propose a biosensor based on photonic crystal fiber made of polymethyl methacrylate using surface plasmon resonance. The proposed sensor consists of a layer of air holes as cladding and a central hole for phase matching between plasmon mode and core guided mode. Alternate holes in the second layer coated with conducting metal oxide, i.e., indium tin oxide (ITO), contain analyte. We found that the optimized thickness of the ITO for optimum performance is 70 nm, which matches with reported result. Unlike other metal coated structures, here the resonance is around telecommunication window and can be tuned by varying the intrinsic properties of the ITO as per requirement. The proposed sensor shows refractive index sensitivity as high as 2000 nm/RIU and has resolution of 5×10^-5 RIU.

An aluminium doped zinc oxide (AZO) coated photonic crystal fiber (PCF) is proposed and numerically analyzed for surface plasmon resonance (SPR) based refractive index (RI) sensing. A microchannel is incorporated in this PCF which is proposed to be fabricated using a pulsed laser. Such type of structure is expected to have less roughness compared to that fabricated by mechanical polishing. Further, properties such as no island formation and absence of intraband transition are added advantages of AZO. Numerical simulation shows that the maximum wavelength sensitivity and the corresponding resolution of this sensor are 5000 nm/RIU and 2×10-5 RIU respectively. Further, the amplitude sensitivity is found to be as high as 167 RIU-1. The proposed structure can be easily fabricated and utilized for sensing applications as it does not require either coating of metals on the inner surface of holes of PCF nor filling of the voids of PCF and it requires a little amount of analyte for RI monitoring.