Ultrathin Pancharatnam–Berry Metasurface with Maximal Cross‐Polarization Efficiency

Abstract

Novel ultrathin dual-functional metalenses are proposed, fabricated, tested, and verified in the microwave regime for the first time. The significance is that their anomalous transmission efficiency almost reaches the theoretical limit of 25%, showing a remarkable improvement compared with earlier ultrathin metasurface designs with less than 5% coupling efficiency. The planar metalens proposed empowers significant reduction in thickness, versatile focusing behavior, and high transmission efficiency simultaneously.

Advances in Full Control of Electromagnetic Waves with Metasurfaces

“…[ 39,40 ] Because of the geometrical nature of the PB phase, such concept can be easily extended to other frequency. [41][42][43] It is noted that the PB phase can only be imparted to CP light. Signifi cantly, when a linearly polarized Figure 1.…”

“…[ 147 ] Nonetheless, generic metasurfaces based on PB phase have a vital defect that the achieved functionalities in controlling EM waves are usually symmetric for two opposite spins, such as focusing/defocusing, left/right and inward/ outward. [ 41,44,46,[145][146][147][148] In principle, each PB phase element (for example, nanorod and nanoslot) acts as a dipole source. To reconstruct a target fi eld distribution, we need to ensure a constructive interference of radiations from different elements, whose spatial distributions are determined by ( , )…”

Surface Impedance Synthesis Using Parallel Planar Electric Metasurfaces

“…Both of them are important and necessary to achieve full control on EM wave propagation [23,24]. The electric surface impedance is usually implemented by ultra-thin metallic patterns [4,14,17,18,[25][26][27], whereas the magnetic surface impedance is usually implemented by the metallic loops [7,23,24,28].…”

“…It is a promising way to manipulate electromagnetic (EM) wave propagation because of the designable feature of its surface impedance, which uniquely determines the EM field behavior. Many novel metasurface devices have been proposed so far, such as planar chiral plates [10], holography [11], spin-controlled photonics [12], wave orbital angular momentum manipulations [13][14][15][16], polarization converters and quarter-wave plates [17,18], flat lens and focusing [19][20][21][22], and Huygens metasurfaces [23,24].…”

Spin-dependent optics with metasurfaces

“…The residual beam, the one not carrying geometric phase, is therefore minimized in its intensity. With optimal design in the transmission geometry, almost 25% efficiency can be achieved by a single-layer nonmagnetic metasurface (see Figure 5A) [82]. Based on the use of three anisotropic sheet metasurfaces (see Figure 5B) [83,84] cascaded along the direction of propagation, the control of vector Bessel beams is proposed with very high efficiency (a beam generator with 20 dB) due to the added magnetic response in the geometric-phase metasurface.…”