  Configurations capable of maximizing both absorptance and polarization
contrast were determined for 1550 nm polarized light illumination of different
plasmonic structure integrated superconducting nanowire single-photon detectors
(SNSPDs) consisting of p=264 nm and P=792 nm periodic niobium-nitride (NbN)
patterns on silica substrate. Global NbN absorptance maxima appear in case of
p/s-polarized light illumination in S/P-orientation (gamma=90 azimuthal angle)
and the highest polarization contrast is attained in S-orientation of all
devices. Common nanophotonical origin of absorptance enhancement is collective
resonance on nano-cavity-gratings with different profiles, which is promoted by
coupling between localized modes in quarter wavelength MIM nano-cavities and
laterally synchronized Brewster-Zenneck-type surface waves in integrated SNSPDs
possessing a three-quarter-wavelength-scaled periodicity. The spectral
sensitivity and dispersion characteristics reveal that device design specific
optimal configurations exist.
