Reversible Tuning of Mie Resonances in the Visible Spectrum

Abstract

Dielectric optical nanoantennas are promising as fundamental building blocks in next generation color displays, metasurface holograms, and wavefront shaping optical devices. Due to the high refractive index of the nanoantenna material, they support geometry-dependent Mie resonances in the visible spectrum. Although phase change materials, such as the germanium–antimony–tellurium alloys, and post-transition metal oxides, such as ITO, have been used to tune antennas in the near-infrared spectrum, reversibly tuning the response of dielectric antennas in the visible spectrum remains challenging. In this paper, we designed and experimentally demonstrated dielectric nanodisc arrays exhibiting reversible tunability of Mie resonances in the visible spectrum. We achieved tunability by exploiting phase transitions in Sb2S3 nanodiscs. Mie resonances within the nanodisc give rise to structural colors in the reflection mode. Crystallization and laser-induced amorphization of these Sb2S3 resonators allow the colors to be switched back and forth. These tunable Sb2S3 nanoantenna arrays could enable the next generation of high-resolution color displays, holographic displays, and miniature LiDAR systems.

Phase-change metasurfaces for dynamic image display and information encryption

“…Employing patterned PCMs in metasurface design is an excellent strategy to obtain a dynamic wavefront control. Despite the great success of GST in reconfigurable meta-devices within the infrared regime, the unconventional Sb 2 S 3 material with a large bandgap of 1.70∼2.05 eV shows a relatively low absorption in the visible spectrum around 600 nm 58,67 .…”

“…For example, the structured GST metasurfaces are reported for bifocal zoom lensing, vortex switching, holographic image switching, cryptography, and so on across the infrared region [50][51][52][53][54][55][56] . And in the visible window, a series of novel PCMs materials including Sb 2 S 3 , Sb 2 Se 3 , and GeSe 3 have been recently successfully employed as nanostructures to realize the dynamically tunable resonances for high-resolution color and beam steering [57][58][59][60][61] . However, the more challenging modulation of optical wavefront over multi-dimensional physical using chalcogenide PCM metasurfaces remains to be demonstrated.…”

“…The most suitable dimensions and orientations of meta-atom can be selected for the three information channels with extra design freedoms. For the sake of practical fabrication, non-reactive dielectric materials like Si 3 N 4 or the conventional resists such as PMMA are usually employed to protect the soft material Sb 2 S 358,61 . Here a Si 3 N 4 film with thickness of t = 70 nm is used to encapsulate the Sb 2 S 3 nanobricks in the design.…”

Low energy switching of phase change materials using a 2D thermal boundary layer

“…However, with the increasing interest in phase change material programmable photonics, we need to start considering how to make these devices switch efficiently too. Some of the most studied applications of PCM-programmable photonics include Si waveguides or plasmonic metamaterials [29][30][31][32][33] . In both cases the PCM is typically interfaced directly with high thermal conductivity materials, both of which have a large thermal conducitivty.…”

“…We study by experiment and simulation whether this inherent thermal property is common to two different TMDCs 2D materials, MoS 2 and WS 2 , and show that these 2D TMDC layers are indeed effective at increasing the optical switching power efficiency in PCM-tuned Si photonic devices. We believe that this design is applicable to a wide range of PCM-based photonic devices, including thin-film reflective displays 38 , programmable plasmonic devices 32 , and metasurfaces 33 .…”