Adjustable microscopic measurement of nanogap waveguide and plasmonic structures

Authors:
Publisher website
Google Scholar
Abstract
We investigate the performance of surface plasmon and Fabry–Perot modes formed between two closely spaced layers. The motivation for this study is twofold: first, to look for modes that may be excited at lower incident angles compared to the usual Kretschmann configuration with similar or superior refractive index responsivity and, second, to develop a simple and applicable method to study these structures over a wide range of separations without recourse to the construction of ad hoc structures. Using back focal plane observation and appropriate signal processing, we show results for the Otto configuration at visible wavelengths at a range of separations not reported hitherto. Moreover, we investigate a hybrid structure we call the Kretschmann–Otto configuration that gives modes that change continuously from a hybridized surface plasmon mode to a zero-order Fabry–Perot mode. The ability to change the separation to small gap distances enables us to examine the Fabry–Perot modes where we show that it has superior refractive index responsivity, by more than an order of magnitude, compared to the Kretschmann configuration.
Funding Information
  • ITF grant (GHP/010/14SZ)
  • Engineering and Physical Sciences Research Council (EPSRC) (EP/G037345/1, EP/L016362/1)
  • PolyU Strategic Importance (1-ZE23)
  • Ningbo Science and Technology Bureau
  • International Doctoral Innovation Centre
  • University of Nottingham

This publication has 16 references indexed in Scilit: