posted on 2021-09-24, 17:33authored byHelena Weigand, Viola V. Vogler-Neuling, Marc Reig Escalé, David Pohl, Felix U. Richter, Artemios Karvounis, Flavia Timpu, Rachel Grange
In display technologies or data processing,
planar and subwavelength
free-space components suited for flat photonic devices are needed.
Metasurfaces, which shape the optical wavefront within hundreds of
nanometers, can provide a solution for thin and portable photonic
devices, for example, as CMOS-compatible modules. While conventional
electro-optic modulators are inconvenient to operate in free space
configurations, its principle can largely be applied to the development
of active metasurfaces with the prospect of modulation speeds up to
the GHz region. We extend this principle of the linear electro-optic
effect to a metasurface in lithium niobate with an optical resonance
in the visible. We exploit the electric and optical field overlap
inside the metasurface to enhance the light matter interaction. Hence,
the modulation of the transmitted light is increased by 2 orders of
magnitude, namely, by a factor of 80, compared to the unstructured
substrate. Furthermore, we investigate the influence of the dispersive
optical resonance on the wavelength-dependence of the modulation and
achieve fast and continuous modulation of light at low voltage and
MHz speed. This proof-of-concept work is a first important step toward
the use of lithium niobate resonant nanostructures for free space
modulation.