Electro-mechanical light modulator based on controlling the interaction of light with a metasurface

Pablo Cencillo-Abad,Nikolay I Zheludev,Jun-Yu Ou,Eric Plum

doi:10.1038/s41598-017-05906-9

Pablo Cencillo-Abad, Nikolay I Zheludev + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-05906-9

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Abstract

We demonstrate a reflective light modulator, a dynamic Salisbury screen where modulation of light is achieved by moving a thin metamaterial absorber to control its interaction with the standing wave formed by the incident wave and its reflection on a mirror. Electrostatic actuation of the plasmonic metamaterial absorber’s position leads to a dynamic change of the Salisbury screen’s spectral response and 50% modulation of the reflected light intensity in the near infrared part of the spectrum. The proposed approach can also be used with other metasurfaces to control the changes they impose on the polarization, intensity, phase, spectrum and directional distribution of reflected light.

Highlights

From their beginnings as microwave frequency selective surfaces[1], metasurfaces have developed into a diverse branch of nanophotonics[2]
We highlight that dynamic control over the spacing of a metasurface of substantially sub-wavelength thickness and a backing mirror provides an effective solution for tuning, modulating and switching the various optical functionalities metasurfaces can provide
The metasurface is an array of asymmetrically split ring apertures in a 50-nm-thick gold layer supported by a 50-nm-thick silicon nitride membrane, see Methods for details

Summary

Introduction

From their beginnings as microwave frequency selective surfaces[1], metasurfaces have developed into a diverse branch of nanophotonics[2]. Such essentially planar arrays of resonators of sub-wavelength size are being used as spectral filters, wave plates[3], polarizers[4, 5] and — based on spatially varying resonators — for redirection[6,7,8] and focusing[9] of light as well as holography[10, 11] Dynamic control over such structures has been achieved by modifying the materials that make up a metasurface, e.g. using phase transitions[12,13,14] or optical nonlinearities[15, 16], by nanomechanical rearrangement of the array of coupled resonators[17, 18], and by controlling the metasurface excitation with counterpropagating coherent beams of light[19]. By placing the metasurface in the standing wave that forms in front of a mirror we create a Fabry-Perot microcavity of variable length that controls the light-metasurface interaction

Methods

Results

Conclusion