Planar segmentation for curved surface plasmon resonance

Surface plasmon resonance (SPR) has been widely exploited for label-free molecular detection in various applications. Despite significant advances in SPR technology, most uses are based on the flat device platform, limiting their scopes of applications. This is because plasmonic devices with a finite radius of curvature are difficult to experimentally implement and require heavy computing resources to analyze. In this report, we carried out calculation of SPR characteristics for curved structures by using segmented-wave analysis which enables calculation of curved plasmonic structures efficiently. We conducted calculation of Au thin film on a curved substrate for the curvature radius in a range of 100 to 3000 um for parallel and perpendicular light incidence in which chord length is fixed regardless of the curvature radius. Reflectance spectra by each segment were obtained using the transfer matrix method based on thin-film optics. This is followed by the results expressed as a discrete sum of segmental results. Then we compared the segmented-wave analysis with the finite element method (FEM) model for validation of results and prove the efficiency of the suggested method. The calculation time of segmented-wave analysis took less than 5 seconds on the personal computer whereas FEM took about 25 hours on the workstation. It was found that the results from the segmentation were in excellent agreement, resonance wavelength in particular, while other parameters such as reflectance and resonance width under parallel incidence showed disparity between the two models in the case of the short segmentation.