All-optical switching of metasurfaces enables dynamic control of the amplitude, phase and the polarization of light at picosecond timescales. The large free-carrier induced permittivity changes in transparent conducting oxides enable all-optical switching at femtosecond to picosecond timescales in planar, unpatterned films, without the need for lithography.
In this work, we experimentally demonstrate the wide-tuning of the optical properties of three materials to achieve fast optical switching with large modulation depth. Lithography-free designs such as Fabry-Perot cavities, metal-dielectric mirrors, and Berreman-type metasurfaces are demonstrated to showcase optical switching at powers on the order of 1 mJ/cm2. The switching speeds can vary from 50 ps in cadmium oxide, 20 ps in ZnO to 2 ps in aluminum-doped zinc oxides. Our work will pave the way to practical optical switching spanning the telecom to the mid-infrared wavelength regimes.
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