Figure 3
Polarization effects in a composite microsphere + GNRs phantom system. Mueller matrix simulated (red symbols) and experimentally obtained (black symbols) variation of the (a) diattenuation and (b) retardance with GNR's aspect ratio \(\in\) for a fixed scattering coefficient of the composite system(\(\upmu_{{_{S} }} = 102\,\hbox{cm}^{ - 1}\) due to microspheres plus \(16\,\hbox{cm}^{ - 1}\) due to GNRs). Increasing diattenuation and retardance with aspect ratio suggests size-dependent increase of the optically anisotropic nature of GNRs. Simulated (red symbols) and experimental (black symbols) variation of diattenuation and retardance with GNRs concentration in a turbid phantom of fixed microsphere scattering properties (diameter = \(0.42\,\upmu\)m, \(\upmu_{S} = 102\,\hbox{cm}^{ - 1}\)). The geometrical parameters of GNRs were length \(l = 70\,\hbox{nm}\) diameter \(d = 25\,\hbox{nm}\)(aspect ratio \(\in = 2.8\)). Both \(D\) and \(R\) exhibit significantly higher values (better contrast) at lower nanorod concentrations (\(\upmu_{S} = 16\,\hbox{cm}^{ - 1}\)), implying strong orthogonal dipolar plasmon polarizabilities even for 3D random orientations of GNRs (for details, see text). The corresponding variation of the simulated and experimental degree of polarization on the GNR concentration shown in (e).
