Metasurface-based broadband polarization-insensitive polarization rotator.

The polarizations of electromagnetic (EM) waves are very important for transceivers. We propose a broadband polarization-insensitive polarization rotator (PIPR), which can realize 90° polarization rotation for incident waves with an arbitrary azimuth angle. A unit of the PIPR is composed of two types of substrate integrated waveguide (SIW) units in a checkerboard pattern, which provides more than -0.2 dB transmission from 9.5 to 10.9 GHz. The electric field inside the cavity is analyzed to explain the working mechanism of the proposed rotator. A prototype is fabricated and measured to verify the proposed design, and satisfactory agreement between simulated and measured results is achieved, indicating that the converter has potential applications in imaging and communication systems.

Asymmetric transmission of acoustic waves in a waveguide via gradient index metamaterials.

We demonstrate that asymmetric acoustic wave transmission in a waveguide can be achieved via gradient index metamaterials (GIMs). We theoretically prove that the acoustic wave can be efficiently converted to surface waves (SWs) via GIMs. The GIMs in a waveguide can allow the transmission of acoustic waves in one direction but block them in the other direction. This theory is validated by experiments. Our findings may provide new applications in various scenarios such as high-efficiency acoustic couplers and noise control.