FDTD numerical analysis of SPR sensing using graphene-based photonic crystal

Abstract

In this study, we investigated the surface plasmon resonance (SPR) sensing based on photonic crystal structures which are designed using a single graphene sheet and multilayer metal oxides (Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and ZnO) for detection sensitivity and the absorption of molecules through excitation wavelength when using air and water as analytes. The refractive index (η) of air is 1.0 and water is 1.33. The method used to investigate the design structure is by simulation using finite difference time domain (FDTD). The wavelength is fixed at 0.8µm (near-infrared region) to excite a transverse electric (TEM) surface plasmon polaritons using Kretschmann configuration. Both analytical and numerical SPR spectra were in a good agreement. When using air as analyte, the reflection of incident angle for Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and ZnO are 59.6° and 62°. While, the reflection of incident angle for Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and ZnO are 69.6° and 71.8° when using water as analyte. The change in the refractive index of the analytes gave a change in the incident angle hence graphene and metal oxides can be used to form a SPR-based biosensor for biomedical applications.