Electrically Tunable Metasurface Perfect Absorbers for Ultrathin Mid-Infrared Optical Modulators


Yu Yao, Raji Shankar, Mikhail A. Kats, Yi Song, Jing Kong, Marko Loncar, and Federico Capasso. 2014. “Electrically Tunable Metasurface Perfect Absorbers for Ultrathin Mid-Infrared Optical Modulators.” NANO LETTERS, 14, 11, Pp. 6526-6532. Publisher's Version


Dynamically reconfigurable metasurfaces open up unprecedented opportunities in applications such as high capacity communications, dynamic beam shaping, hyperspectral imaging, and adaptive optics. The realization of high performance metasurface-based devices remains a great challenge due to very limited tuning ranges and modulation depths. Here we show that a widely tunable metasurface composed of optical antennas on graphene can be incorporated into a subwavelength-thick optical cavity to create an electrically tunable perfect absorber. By switching the absorber in and out of the critical coupling condition via the gate voltage applied on graphene, a modulation depth of up to 100% can be achieved. In particular, we demonstrated ultrathin (thickness < lambda(0)/10) high speed (up to 20 GHz) optical modulators over a broad wavelength range (5-7 mu m). The operating wavelength can be scaled from the near-infrared to the terahertz by simply tailoring the metasurface and cavity dimensions.
Last updated on 05/24/2020