Multistable elastic pixels: nematic elasticity for non-volatile positioning of colloidal optical scatterers

Abstract

Non-volatile reconfiguration of optical devices, in which a configuration persists without continuous energy input, remains a challenge. We introduce multistable elastic pixels (MEPs), lithographically defined pores filled with a nematic liquid crystal, whose curved ends capture a scattering inclusion in one of two mechanically stable sites. Simulations and experiments show that pore geometry and homeotropic surface anchoring define the energy minima and the height of the barrier between them. This barrier far exceeds thermal energies, stabilizing a scatterer location absent an external field. Colloidal inclusions switch reversibly between sites under transient electric fields. Using arrays of static scatterers, we show that the two positional states produce distinct responses at visible wavelengths, demonstrating the potential of MEPs for reconfigurable devices and metasurfaces. Unlike phase-change and liquid-crystal-tuned approaches, which switch a material surrounding fixed scatterers, MEPs use the nematoelastic energy landscape to move the optical element itself.