The optimum orientations were determined for polarized light illumination of three superconducting nanowire single-photon detector (SNSPD) designs consisting of niobium-nitride (NbN) stripes with dimensions according to conventional devices in 200 nm periodic pattern: (1) standing in air (bare-SNSPD), (2) below hydrogen-silsesquioxane (HSQ) filled nano-cavity (DC-SNSPD), and (3) below HSQ-filled nano-cavity closed by a thin gold reflector (OC-SNSPD). Computations showed that the optical response and near-field distribution vary significantly with polar angle , and these variations are analogous across all azimuthal angles , but are fundamentally different in different device designs. Larger absorptance is attainable due to -polarized illumination of NbN patterns in -orientation, while -polarized illumination results in higher absorptance in -orientation. As a result of -polarized illumination, a global NbN absorptance maximum appears in bare-SNSPD at polar angle corresponding to attenuated total internal reflection (ATIR); in DC-SNSPD exactly at total internal reflection (TIR); and at perpendicular incidence in OC-SNSPD. -polarized illumination results in a global NbN absorptance maximum in bare-SNSPD at TIR; in DC-SNSPD at polar angle corresponding to ATIR phenomenon; while large and almost polar angle independent absorptance is attainable in OC-SNSPD at small tilting.