Previous studies on hybrid dielectric-graphene metasurfaces have been used to implement induced transparency devices, while exhibiting high Q-factors based on trapped magnetic resonances. Typically, the transparency windows are single wavelength and less appropriate for polarization conversion structures. In this work, a quarter-wave plate based on a hybrid silicon-graphene metasurface with controllable birefringence is numerically designed. The phenomena of trapped magnetic mode resonance and high Q-factors are modulated by inserting graphene between silicon and silica. This results in a broader transmission wavelength in comparison to the all-dielectric structure without graphene. The birefringence tunability is based on the dimensions of silicon and the Fermi energy of graphene. Consequently, a linear-to-circular polarization conversion is achieved at a high degree of 96%, in the near-infrared. Moreover, the polarization state of the scattered light is switchable between right and left hand circular polarizations, based on an external gate biasing voltage. Unlike in plasmonic metasurfaces, these achievements demonstrate an efficient structure that is free from radiative and ohmic losses. Furthermore, the ultrathin thickness and the compactness of the structure are demonstrated as key components in realizing integrable and CMOS compatible photonic sensors.

A polarization-sensitive V-shaped slot nanoantenna column is utilized to realize tunable unidirectional coupling of surface plasmon polaritons (SPP). Two plasmon resonant modes are excited in the V-shaped slot nanoantennas with xand y-polarized incident light, respectively. The electric fields of coupled SPP show different symmetries corresponding to that of the two resonant modes. Linear combinations of the two resonant modes result in asymmetric SPP intensity distributions. As a result, by controlling the incident polarizations, tunable unidirectional coupling of SPP to two opposite directions perpendicular to the column at different wavelengths are realized. A highest extinction ratio of 36.7 dB is achieved, and the extinction ratio keeps larger than 7 dB within a wavelength of 149 nm.

A method to detect the full Stokes parameters utilizing a double-ring and Archimedes-curves distributed nanoslits plasmonic lenses is proposed. We demonstrate theoretically and numerically that both of these two plasmonic lenses can focus surface plasmon polaritons to centrally symmetric fields with subwavelength-sized focal spots under linear, elliptical, and circular polarization incidence. The intensity at the focal spots is modulated by the polarization state of incident light. Utilizing this intensity polarization sensitivity, the full Stokes parameters of incident light are detected by recoding only four intensities at the focal spots of these two plasmonic lenses.

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