Fig 1.
Schematic representations of attenuated total reflection.
a) the Otto configuration; b) the Kretschmann configuration; c) the Kretschmann configuration with the addition of a low-index coupling layer, as reported here.
Fig 2.
Dispersion relationships for a single gold film.
a) the standard Kretschmann configuration; b) the Kretschmann configuration with the addition of a dielectric spacer layer. Shown are the SPP modes (black) and the relevant light lines. The area shaded grey is the region in which leaky modes are found.
Fig 3.
Schematic structure of the device reported in this study showing the defined internal angle.
Fig 4.
Schematic of the attenuated total reflectance experimental setup used in this study.
Fig 5.
ATR reflectance as a function of excitation wavelength shown for a range of internal angles (50 to 61 degrees in one-degree increments).
Shown are experimental measurements (symbols) together with model results (lines) for corresponding internal angles.
Table 1.
Fitting parameters and the values obtained from fitting the ATR scans shown in Fig 5.
Fig 6.
Calculated dispersions generated both with (black lines) and without (blue lines) damping included in the gold dielectric function.
Shown are the light lines for the relevant dielectric materials and the minima (red dots) of the measured ATR curves (see Fig 5).
Fig 7.
Magnification of experimentally-relevant dispersion region in Fig 6 and electric field amplitudes.
a) the experimentally relevant region of the dispersion displayed in Fig 6; b) electric field amplitude (modulus squared) associated with point b on the dispersion plot; c) electric field amplitude (modulus squared) associated with point c on the dispersion plot. Red dots indicate the minima of the experimental ATR scans (see Fig 5).
Fig 8.
Calculated propagation length as a function of frequency (top panel) and undamped dispersion relationship (bottom panel).
Red dots indicate the minima of the experimental ATR scans (see Fig 5).
Fig 9.
Magnification of lower frequency dispersion region in Fig 6 and electric field amplitudes.
a) the lower frequency region of the dispersion displayed in Fig 6; b) electric field amplitude (modulus squared) associated with points i and ii on the dispersion plot; c) electric field amplitude (modulus squared) associated with points iii and iv on the dispersion plot.
Fig 10.
Propagation length and as a function of frequency.
a) Propagation length as a function of frequency for the full range of frequencies, as well as focused on the low frequency region (inset); b) A portion of the dispersion displayed in Fig 6, focused on the experimentally relevant region. Several points (i-iv) are shown on both plots for comparison.