40
S. Droulias and L. Bougas
Fig. 2.8 Measurement sensitivity of θ on the chirality parameter κ. a Angle-resolved R p
reflectance denoting the SPR angle (θ SPR ) for the shown selected values of n c with κ = 0. b
vs SPR angle. The solid black line represents a multitude of individual calculations, on which the
cases for n c shown in (a) are marked with dots of the same colour. c θ vs κ for the selected values
of the host index n c . The solid black line denotes the system of Fig. 2.6 with n c = 1.33
Fig. 2.9 θ//κ as a function of the chiral-layer thickness, for κ = 0.1. The dashed black line
represents the results shown in Fig. 2.8
sented in Fig. 2.8b, for chiral layers of variable thickness. We see that, with increasing
chiral layer thickness, the measurement sensitivity converges to the limit of chiral
substances of theoretically infinite extent (practically referring to electrically thick
samples). In addition, we observe that for small SPR angles this increase is monotonic, but for large SPR angles the measurement sensitivity reaches a maximum level
for a thickness of ∼100–150 nm, beyond which it gradually drops until convergence.
Therefore, we see that due to the evanescent character of the SPP wave inside the chiral region, one can achieve through measurements of θ similar levels of sensitivity
for a large range of chiral-layer thicknesses.
2.3.3 Differential Measurements
In the previous subsections we demonstrate how the presence of a thin chiral layer
results in a chiral-dependent angular split between the measured reflectances of R +
S. Droulias and L. Bougas
Fig. 2.8 Measurement sensitivity of θ on the chirality parameter κ. a Angle-resolved R p
reflectance denoting the SPR angle (θ SPR ) for the shown selected values of n c with κ = 0. b
vs SPR angle. The solid black line represents a multitude of individual calculations, on which the
cases for n c shown in (a) are marked with dots of the same colour. c θ vs κ for the selected values
of the host index n c . The solid black line denotes the system of Fig. 2.6 with n c = 1.33
Fig. 2.9 θ//κ as a function of the chiral-layer thickness, for κ = 0.1. The dashed black line
represents the results shown in Fig. 2.8
sented in Fig. 2.8b, for chiral layers of variable thickness. We see that, with increasing
chiral layer thickness, the measurement sensitivity converges to the limit of chiral
substances of theoretically infinite extent (practically referring to electrically thick
samples). In addition, we observe that for small SPR angles this increase is monotonic, but for large SPR angles the measurement sensitivity reaches a maximum level
for a thickness of ∼100–150 nm, beyond which it gradually drops until convergence.
Therefore, we see that due to the evanescent character of the SPP wave inside the chiral region, one can achieve through measurements of θ similar levels of sensitivity
for a large range of chiral-layer thicknesses.
2.3.3 Differential Measurements
In the previous subsections we demonstrate how the presence of a thin chiral layer
results in a chiral-dependent angular split between the measured reflectances of R +