PRApplied Editors’ Suggestion (15-Jul-2021)

Our paper on metagratings for perfect mode conversion in rectangular waveguides by postdoctoral fellow Dr. Vinay Kumar Killamsetty and Ariel Epstein was published in the Physical Review Applied, and was selected to be highlighted as Editors’ Suggestion. The paper extends the metagrating synthesis approach to enable complete power transfer from an incident TE10 mode into a reflected TE20 mode within a metallic waveguide. The analytical design is based on the analogy between beam interaction with a periodic surface and the effective periodicity formed by the metallic waveguide walls. The method points out favorable positions for a capacitively loaded wire, and the geometry of the load printed capacitor, to facilitate perfect mode conversion. The resultant fabrication-ready design (in the form of a small PCB card) is manufactured without any further optimization, and characterized using two different setups – S-parameter measurement with a VNA, and radiation pattern characteristics of the open-ended waveguide. Despite being fundamentally different, both measurements excellently agree with each other, pointing out that the fabricated prototype successfully couples more than 90% of the input power into the higher-order mode. These results form an original alternative to common mode converters, typically relying on structural deformation and extensive numerical optimizations.

APL Editor’s Pick (29-Mar-2021)

Our invited paper on nonradiative subdiffraction near-field patterns using metagratings by PhD student Oshri Rabinovich and Ariel Epstein was published as part of a Special Topic collection in Applied Physics Letters, and was selected to be highlighted as Editor’s Pick. The paper shows that metagratings can exercise meticulous control not only over propagating fields, but also on evanescent wave scattering. By proper adjustments of our previously derived formalism, we design several metagrating devices that produce prescribed periodic near-field patterns with deep subwavelength features, with negligible loss due to absorption or undesired forward radiation. The diverse patterns, exclusively formed by interference of multiple surface waves, allow, in principle, near-unitary power recycling, which may be highly useful for nonradiative wireless power transfer, subdiffraction imaging, and high-resolution alignment (as demonstrated in the Supplementary Material).

PRApplied Paper Published (9-Dec-2020)

Our paper “Dual-polarized all-metallic metagratings for perfect anomalous reflection” by PhD student Oshri Rabinovich and A. Epstein,  has been published in the Physical Review Applied. The paper utilizes an analytical formalism to control scattering from a periodic arrangements of grooves made in a metallic slab, showing (both theoretically and experimentally) that anomalous reflection can be efficiently achieved with this all-metallic structure. In addition to the simple two-channel anomalous reflection, the model is able to tackle scenarios with multiple diffraction orders by utilizing multiple (different) grooves per period. Dual-polarized operation is also feasible with this configuration, as demonstrated as well, and fundamental limitations related to manipulating transverse electric fields are revealed and discussed. The results enable harnessing the metagrating appealing semianalytical design schemes for applications where all-metallic structures are preferred, such as high-frequency systems and spaceborne apparatus.