Long-range surface plasmon resonance enhanced transmission of light through silver-coated Cytop gratings

Abstract

In this study, transmission surface plasmon resonance (TSPR) signal of a silver-coated Cytop grating/glass slide substrate was investigated in combination with a hyperspectral imaging technique. The TSPR excitation peaks, corresponding to surface plasmon (SP) dispersion modes of +2 (−SP+2) and −1 (+SP−1), were simultaneously observed. The TSPR signal of −SP+2 mode at the visible light region was further enhanced by increasing Cytop thickness. A 2-time stronger in TSPR intensity of the developed substrate than that of conventional silver-coated polycarbonate grating substrate was observed. Since the structure of the substrate was the silver film bound by Cytop and water that had similar dielectric constants, this enhancement was due to a long-range SP resonance effect. TSPR hyperspectral image of developed substrate while injecting different concentrations of ethylene glycol solutions into a five-microchannel assembled to the substrate were recorded and TSPR hyperspectra were then plotted to acquire the sensitivity of this technique. This technique gave a sensitivity of 315.0 nm RIU−1. According to the sensitive changes of TSPR hyperspectral image to the refractive index of an environment, this technique showed high potential with respect to further development of sensing devices based TSPR imaging system.