2. Modeling
We calculate changes in the polarization state of a light beam
interacting with a layer of VO2 as the material undergoes a phase
transition. To this end, we assume a monochromatic plane wave
incident on a uniform and homogeneous layer of VO2 deposited on
a semi-infinite dielectric substrate. Reflection and transmission
coefficients at air/VO2 and VO2/substrate interfaces are given by
Fresnel's equations and assume the refractive indices to be uniform
throughout the film. We will also assume that the polarization
of incident light can be prepared in any arbitrary state. Fig. 1
defines the parameters of the problem. Here θi is the incident
angle, E⃑
o, E⃑
r and E⃑
t the complex electric field of the oncoming,
reflected and transmitted waves, respectively. The VO2 layer is
assumed to have a complex refractive index n ik + and be deposited
on a dielectric substrate. The electric field component
parallel to the plane of incidence is the p-polarization and the
component perpendicular to it is the s-polarization. For convenience,
we chose to express the electric field in the basis of sand
p-polarizations.
We first treat the case of reflection, then expand the results to