  Herein, the concept of point of darkness based on polarized light phase
difference and absorption of light is demonstrated by simulations using low
refractive index and extinction coefficient semiconductor and dielectric, and
high refractive index nonoxidizing metal multilayer thin film structures.
Several multilayer sensor configurations show great sensitivity to thickness
and refractive index variation of the detectable material by measuring the
reflectivity ratio {\Psi} and phase shift {\Delta}. Focus is on such
multilayers, which have sensitivity to both parameters ({\Psi}, {\Delta}) in
the visible spectral range, thus opening the possibility for further research
on a new biomedical sensor development with enhanced double parameter sensing.
