Active control of anapole states by structuring the phase-change alloy Ge2Sb2Te5

• Published in: Nature communications Vol. 10; no. 1; pp. 396 - 9
• Main Authors: Tian, Jingyi, Luo, Hao, Yang, Yuanqing, Ding, Fei, Qu, Yurui, Zhao, Ding, Qiu, Min, Bozhevolnyi, Sergey I.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.01.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 132/122; 140/125; 142/126; 147/135; 147/3; 639/624/399; 639/766/1130/2799; Active control; Broadband; Electric dipoles; Humanities and Social Sciences; Investigations; multidisciplinary; Nanoparticles; Optical switching; Phase change materials; Physics; Radiation; Resonance; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-08057-1

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 2 Sb 2 Te 5 (GST) can support a diverse set of multipolar Mie resonances with active tunability. By harnessing the dramatic optical contrast of GST, we realize broadband (Δ λ / 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. High-index dielectric nanoparticles support a great wealth of multipolar responses but active tunability is still elusive. Here, the authors report how structured Ge 2 Sb 2 Te 5 can support multipolar Mie resonances and demonstrate the spectral shifting between electric dipole and anapole modes.