A novel multi-focusing metalens in the longitudinal direction has been proposed and investigated based on the equal optical path principle, which is independent on the incident polarizations and can be suitable for both of the linear and circular polarization incidences simultaneously. Here, three novel designing principles: partitioned mode, radial alternating mode and angular alternating mode, have been proposed firstly for constructing different types of the longitudinal multi-focusing metalenses. The performances of the designed metalenses based on the different designed methods have also been analyzed and investigated in detail, and the intensity ratio of the focusing spots can be tuned easily by modulating the numbers of the relative type of nanoantennas, which is significant for the micro-manipulating optics and the multi-imaging technology in the integrated optics.
We propose an ultra-thin metasurface of the metal rectangular split-ring resonators (MRSRR) array which can modulate and analyze the wavefront of circularly polarized light efficiently. An incident circularly polarized light could be converted into the corresponding cross-polarized light which would be bent to ± 23° at a wavelength of 808 nm for the normal incidence. And a linearly polarized light would be decomposed into two lights of left and right-handed circular polarizations in the directions of ∓23° respectively. These phenomena have also been observed at 1200 nm with different geometric parameters. And these results depend on controlling the optical-axis profile of the resonators in a subwavelength scale by precisely modulating two degrees of freedom in our nanostructures.
In this paper, we reviewed our recent work on the statistical properties of polarization speckle, described by stochastic Stokes parameters fluctuating in space. Based on the Gaussian assumption for the random electric field components and polar-interferometer, we investigated theoretically and experimentally the statistics of Stokes parameters of polarization speckle, including probability density function of Stokes parameters with the spatial degree of polarization, autocorrelation of Stokes vector and statistics of spatial derivatives for Stokes parameters.
A new type of optical polarization converter based on the L-shaped gold nanoantenna array supercell has been presented, which is suitable for both circular and X/Y linear polarization conversion simultaneously. Both the amplitude and phase of transmitted cross-polarization light can be modulated precisely by changing the lengths and widths of the L-shaped nanoantenna units. For circular or X/Y linear polarization incident lights, the corresponding cross-polarized lights can be obtained in the transmitted lights, and the corresponding bending angles of the cross-polarized lights can be modulated by the structures and the incident angles according to the generalized Snell’s law. The multi-spectral characteristics have also been investigated, in which the operating bandwidth of the designed optical polarization converter is 450 nm (in the range of 750 ∼ 1200 nm).
We have proposed a carefully designed metasurface constructed by the elongated apertures in gold film. This metasurface structure can support only single anomalous refractions for both circular polarization (CP) and linear polarization (LP) incidence, which is also following the generalized Snell's law, whereas the normal refraction can be completely suppressed nearly. Furthermore, the circularly polarized light converted to cross-polarized light and the linearly polarized light decomposed into two CP states with opposite transmission angle after passing through the metasurface with a high conversion efficiency of 87.5 %. The concept of single anomalous refraction can be exploited for creating high-performance wave plate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.