Kwon Hyounghan, Faraon Andrei
T. J. Watson Laboratory of Applied Physics and Kavli Nanoscience Institute, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
Department of Electrical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
ACS Photonics. 2021 Oct 20;8(10):2980-2986. doi: 10.1021/acsphotonics.1c00898. Epub 2021 Sep 8.
Active control of strong chiroptical responses in metasurfaces can offer new opportunities for optical polarization engineering. Plasmonic active chiral metasurfaces have been investigated before, but their tunable chiroptical responses is limited due to inherent loss of plasmonic resonances, thus stimulating research in low loss active dielectric chiral metasurfaces. Among diverse tuning methods, electrically tunable dielectric chiral metasurfaces are promising thanks to their potential for on-chip integration. Here, we experimentally demonstrate nano-electromechanically tunable dielectric chiral metasurfaces with reflective circular dichroism (CD). We show a difference between absolute reflection under circulary polarized incident light with orthogonal polarization of over 0.85 in simulation and over 0.45 experimentally. The devices enable continuous control of CD by induced electrostatic forces from 0.45 to 0.01 with an electrical bias of 3V. This work highlights the potential of nano-electromechanically tunable metasurfaces for scalable optical polarization modulators.
在超表面中主动控制强手性光学响应可为光学偏振工程带来新机遇。此前已对等离子体有源手性超表面进行了研究，但由于等离子体共振的固有损耗，其可调谐手性光学响应受到限制，从而激发了对低损耗有源介电手性超表面的研究。在各种调谐方法中，电可调谐介电手性超表面因其片上集成潜力而颇具前景。在此，我们通过实验展示了具有反射圆二色性（CD）的纳米机电可调谐介电手性超表面。我们表明，在模拟中，圆偏振入射光下正交偏振的绝对反射率之差超过0.85，实验中超过0.45。这些器件通过3V的电偏置，利用感应静电力实现了从0.45到0.01的圆二色性连续控制。这项工作突出了纳米机电可调谐超表面在可扩展光学偏振调制器方面的潜力。
