Mechanically reprogrammable Pancharatnam–Berry metasurface for microwaves

Abstract

Metasurfaces have enabled the realization of several optical functionalities over an ultrathin platform, fostering the exciting field of flat optics. Traditional metasurfaces are achieved by arranging a layout of static meta-atoms to imprint a desired operation on the impinging wavefront, but their functionality cannot be altered. Reconfigurability and programmability of metasurfaces are the next important step to broaden their impact, adding customized on-demand functionality in which each meta-atom can be individually reprogrammed. We demonstrate a mechanical metasurface platform with controllable rotation at the meta-atom level, which can implement continuous Pancharatnam-Berry phase control of circularly polarized microwaves. As the proof-of-concept experiments, we demonstrate metalensing, focused vortex beam generation, and holographic imaging in the same metasurface template, exhibiting versatility and superior performance. Such dynamic control of electromagnetic waves using a single, low-cost metasurface paves an avenue towards practical applications, driving the field of reprogrammable intelligent metasurfaces for a variety of applications.

Spin‐Decoupled Interference Metasurfaces for Complete Complex‐Vectorial‐Field Control and Five‐Channel Imaging

“…Furthermore, our method is universal which is compatible with mechanical technology to achieve dynamic complete control and associated meta-devices, such as in the microwave regime where mechanical rotation in the unit-cell level is possible. [41,42] In summary, we have proposed and demonstrated a generic designing strategy for achieving complete CVF control, including its amplitude, phase and polarization properties, based on spindecoupled interference metasurfaces controlled by the PB phase mechanisms in the terahertz regime. The basic meta-molecule of the interference metasurface only contains two pairs of independently rotating meta-atoms made of silicon pillars with HWP feature and 𝜋/2 overall relative phase shift.…”

Broadband Wide Field-of-View Metalens by the Virtual-Diffraction-Aperture Method

“…Recently, various metasurfaces have progressively sprung up as new devices for modulating electromagnetic (EM) fields at subwavelength spatial resolution through patterned elements on a flat surface. − Metalens, a specific case of the metasurface, has emerged as the focusing component of advanced imaging systems and has received growing interest, owing to its subwavelength thickness and diverse functionalities. − Versatile metalens-enabled devices have been designed and realized in an ultra-compact configuration, becoming significant as the demand for high-performance and low-cost miniaturized devices rapidly increases. − The metalens commercialization is, unfortunately, affected by different aberrations, resulting in, for example, deteriorated image resolution and limited field-of-view (FOV). , …”

Stereo Metasurfaces for Efficient and Broadband Terahertz Polarization Conversion

“…[20][21][22][23][24] In particular, the orthogonal polarization converters can endow local circularly polarized (CP) outputs with dispersion-less Pancharatnam-Berry (PB) phases determined by the meta-atom orientation. [25][26][27] Such a method allows the integration of both polarization conversion and wavefront control functionalities within single planar devices, and has elicited great research enthusiasm in developing compact THz devices, such as meta-gratings, [28][29][30] metalenses, [31,32] special beam generators, [28,33] metaholograms, [34,35] and surface plasma launchers. [36] Among these demonstrations, pursuing highefficiency and broadband performances becomes a research frontier.…”