Active control of anapole states by structuring the phase-change alloy Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30674900.
- Also identified by DOI 10.1038/s41467-018-08057-1 and PMC identifier 6344509.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
High-index dielectric nanoparticles supporting a distinct series of Mie resonances have enabled a new class of optical antennas with unprecedented functionalities. The great wealth of multipolar responses has not only brought in new physical insight but also spurred practical applications. However, how to make such a colorful resonance palette actively tunable is still elusive. Here, we demonstrate that the structured phase-change alloy Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> (GST) can support a diverse set of multipolar Mie resonances with active tunability. By harnessing the dramatic optical contrast of GST, we realize broadband (Δλ/λ ~ 15%) mode shifting between an electric dipole resonance and an anapole state. Active control of higher-order anapoles and multimodal tuning are also investigated, which make the structured GST serve as a multispectral optical switch with high extinction contrasts (>6 dB). With all these findings, our study provides a new direction for realizing active nanophotonic devices.