**10. Conclusion**

This chapter contains a clear, yet rigorous, picture as to how the real physical causes behind all these macroscopic optical phenomena – i.e., the microscopic electric and magnetic dipoleswork to come up with such macroscopic results. Both the electric and magnetic dipoles react to the imposed EM wave in such a way that actually results in the Fresnel equations.

In arriving at the more intuitive "scattering form" of the Fresnel equations, microscopic EMinduced physical electric and magnetic dipoles were rigorously employed as the source of electromagnetic waves by Doyle et al. Motivated by such an approach, the authors started to speculate how the incorporation of permanent dipoles might affect many macroscopic optical phenomena, e.g., the Brewster angle of a specific optical material. Among its predictions, the traditionally fixed Brewster angle of a specific material now not only becomes dependent on the density and orientation of incorporated permanent dipoles, but also on the incident light intensity (more precisely, the incident wave electric field strength). Further, two conjugated incident light paths would give rise to different refracted wave powers. This kind of microscopic approaches are called "dipole engineering".

Theoretical elaboration and then IR experiments on poled polyvinylidene fluoride (PVDF) films were conducted to verify the emergence of asymmetric reflections at varying incident angles, as well as the inverse dependence of reflectivity upon the impinging light intensity. In addition, experiments on dipole-engineered PVDF films show that by way of adding/reducing permanent dipole density and varying orientations, the aforementioned theoretical predictions can be evidenced unambiguously in the visible light range. Further, effective polarization density can be quantified from the above experiments subjected to different dipole engineering processes. As a result, the traditionally elliptic contour of a slanted two dimensional section of the refractive index ellipsoid now manifests symmetric open splittings at near the traditional incident angle. It implies that severe challenge to the accuracy of traditional surface plasmon resonance measurements may arise in the presence of permanent dipoles of various morphologies, such as in the forms of nano-particles or membrane double layers.

Traditional approach of obtaining electric permittivity through directly measuring a material's refractive index begins to appear flawed at dawn of the nanotech era. On the other hand, achieving novel magnetics and thus new materials of variable refractive indices starts to become meaningful. However, unlike its electric counterpart, data for optical magnetic permeability is hardly available for most materials. An effective method is proposed to secure practically accurate optical permeabilities through manipulating electronic transition rates generated by first-principle quantum mechanical simulations.
