Reversible Thermal Tuning of High-Q Non-Local Lithium Niobate Metasurfaces

Dynamic control of optical resonances in metasurfaces has become increasingly critical, driven by the growing demand for tunable photonic devices across a wide range of modern nanophotonics applications, including optical switches, displays, and optical communications. Lithium niobate (LN) metasurfaces, featuring a broad transparency window and low optical loss, offer a promising platform for realizing tunable and reconfigurable nanophotonics systems. However, conventional electro-optic tuning of LN is often limited by high-voltage requirements and fabrication constraints. In this work, the authors demonstrate reversible thermal tuning of high-quality factor (high-Q) guided mode resonances and quasi-bound states in the continuum (quasi-BICs) in LN metasurfaces. By employing high-Q resonances, the thermo-optic and thermal expansion response is enhanced, achieving modulation of the reflection spectrum from 0 to 1 over an 85 (Formula presented.) temperature range. At a fixed wavelength, the system exhibits a thermal modulation sensitivity of 1.176% per (Formula presented.), allowing for precise and repeatable spectral control. This dual-channel tuning approach offers precise, reversible control of the optical spectrum. These thermally reconfigurable LN metasurfaces present a robust platform for optical filtering, sensing, and active photonic circuitry. These findings pave the way for thermally reconfigurable metasurfaces, expanding the functional scope of LN-based nanophotonic devices.