Ultra-compact bifunctional transparent meta-device based on bi-layer anisotropic Huygens’ metasurface

Bifunctional transparent meta-devices play an essential role in electromagnetic (EM) integration because of their advantages in extensive applications in modern devices. However, most available devices are achieved by multi-layer dielectric cascaded structures due to the requirement of 360° transmission phase shift, which suffer from the issues of high loss, complex mode control, complicated fabrication and device-integration inconvenience. Herein, a bi-layer anisotropic Huygens' metasurface is proposed to design ultra-compact bifunctional transparent meta-devices based on the polarization dependent property via inducing the orthogonal electric and magnetic currents simultaneously to excite the Huygens' resonance. As proof of the concept, a bifunctional transparent meta-device is designed, fabricated and experimentally demonstrated, which behaves as a beam deflector and a focusing lens under excitation of x-polarized and y-polarized incident waves, respectively. Numerical results coincide well with the experiments, indicating that the measured total efficiency of the beam deflector is about 64% at 10 GHz and the measured relative efficiency of the focusing lens achieves about 80%. Our findings provide a novel low-cost, easy-to-fabricate and convenient-to-setup solution for bifunctional transparent meta-devices and could stimulate their promising applications in many EM integration systems.