Abstract
We experimentally and theoretically investigate Fano-like resonance in large-area Au/SiO2/Au nano-patches meta-structure, which is originating from the coupling between Fabry Perot resonance and magnetic dipole resonance modes. A highly sensitive refractive index sensor based on the lineshape analysis is obtained. The extracted wavelength shift with the amount of substance of Hg2+ changing from 10-3 pmol to 1 nmol has a linear dependence, and the sensitivity can reach to ultra-low limit of detection (LOD) as 10-3 pmol. This study may provide an approach for the development and modification in sensing.
A Mach–Zehnder interferometer (MZI) based on an etched all-solid microstructure fiber (MOF) has been demonstrated. The MZI works on the basis of interference between the vibrant core and cladding modes in the MOF. The all-solid MOF has a heterostructure cladding composed of Ge-doped rod arrays and pure silica, and thus can support and propagate a vibrant cladding mode with a large mode area. When the outermost cladding of MOF is etched, the cladding mode becomes sensitive to the ambient refractive index (RI). The etched MOF can work as a sensing head for RI sensing. By comparing the interference spectra, the extinction ratio has remained stable at around 20 dB after the MOF was etched. The RI sensing characteristics of the MZI with an etched MOF have also been investigated. The results show that the RI sensitivity can reach up to 2183.6 nm/RIU with a low-temperature coefficient (<10 pm/°C).
A highly sensitive SPR refractive index sensor based on microfluidic channel assisted with graphene-Ag composite nanowire
