Thermoplasmonic Controlled Optical Absorber Based on a Liquid Crystal Metasurface

Area of Science:

• Nanophotonics and Metamaterials
• Liquid Crystal Photonics
• Optical Absorber Technology

Background:

• Metasurfaces, composed of subwavelength elements, offer excellent optical properties but lack dynamic tunability.
• Existing metasurfaces are limited in their ability to function as adaptive optical components.
• There is a need for dynamically controlled optical devices utilizing metasurface technology.

Purpose of the Study:

• To develop a tunable metasurface-based optical absorber.
• To integrate nematic liquid crystals (NLCs) with a metasurface for dynamic control.
• To demonstrate a light-controllable optical absorber with tunable absorption bands.

Main Methods:

• Fabrication of a metasurface using self-assembled silver nanocubes (AgNCs) on a gold layer with a polyelectrolyte dielectric spacer.
• Integration of the metasurface with a planarly aligned nematic liquid crystal (NLC) layer via photoaligned substrate.
• Spectroscopic and thermographic investigations to characterize optical properties and tunability.

Main Results:

• The fabricated optical absorbers exhibited a distinct reflection band in the near-infrared (750-770 nm).
• High absorption efficiency (∼60%) at the resonant wavelength and significant photothermal efficiency (time constant 34 s) were observed.
• The combined metasurface-NLC system demonstrated a photothermally tunable absorption band over approximately 46 nm.

Conclusions:

• The developed metasurface-NLC hybrid structure provides a highly effective and tunable optical absorber.
• This active metasurface exhibits extraordinary capability for light-controllable absorption.
• The findings enable the development of a new generation of dynamically controlled adaptive optical components.