A variant of surface plasmon resonance (SPR) spectroscopy has been developed that involves a coupling of plasmon resonances in a thin metal film and waveguide modes in s dielectric overcoating. This new technique is referred to as coupled plasmon-waveguide resonance (CPWR) spectroscopy. It combines a greatly enhanced sensitivity (due to increased electromagnetic field intensities at the dielectric surface) and spectral resolution (due to decreased resonance linewidths), with the ability to directly measure anisotropies in refractive index and optical absorption coefficient in a dielectric film adsorbed onto the surface of the overcoating. Experimental data obtained with an egg phosphatidylcholine bilayer are presented to document these properties.
Salamon, Z., Macleod, H. A., & Tollin, G. (1997). Coupled plasmon-waveguide resonators: A new spectroscopic tool for probing proteolipid film structure and properties. Biophysical Journal, 73(5), 2791–2797. https://doi.org/10.1016/S0006-3495(97)78308-5