Tunable transmissive metasurface based on thin-film lithium niobate

TL;DR

This paper introduces a tunable transmissive metasurface using thin-film lithium niobate with integrated transparent electrodes, demonstrating electro-optic resonance tuning and angle-based modulation for advanced light control.

Contribution

It presents a novel free-space transmissive light modulator based on un-patterned thin-film lithium niobate with integrated meta-gratings, enabling high-precision electro-optic tuning.

Findings

Resonance shift of 0.38 nm under ±10 V bias

Maximum modulation amplitude of 4.6%

Resonance splitting via incident angle variation

Abstract

Active metasurfaces hold great promise for spatial light modulation, and electro-optic tuning using lithium niobate is particularly attractive due to its high transparency and well-established thin-film platform. In this work, we present a free-space transmissive light modulator based on a seemingly un-patterned thin-film lithium niobate-on-insulator platform, integrated with a transparent conductive oxide meta-grating fabricated through a single lithography process. Guided mode resonance in the near-infrared region is induced with high mode confinement within lithium niobate layer, which directly in contact with the electrodes. A notable resonance shift of 0.38 nm is observed for the fundamental mode under +-10 V bias, while a maximum modulation amplitude of 4.6% is achieved for another higher-order mode. Incident angle is further exploited as another tuning parameter to split and sensitively shift the resonances. These results demonstrate the potential of this design for applications in compact, scalable, and tunable spatial light modulation devices.