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

Jingyi Tian,Yurui Qu,Fei Ding,Hao Luo,Yuanqing Yang,Min Qiu,Ding Zhao,Sergey I Bozhevolnyi

doi:10.1038/s41467-018-08057-1

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 Ge2Sb2Te5 (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.

Highlights

High-index dielectric nanoparticles supporting a distinct series of Mie resonances have enabled a new class of optical antennas with unprecedented functionalities
A detailed multipole analysis further shows that the scattering maxima and minima are ambiguously attributed to the electric dipole (ED) and anapole states, respectively (Fig. 1c)
We revealed that the high index and the dramatic optical contrast of the GST material empower its nanostructures to support a distinct series of Mie resonances with active tunability

Summary

Introduction

High-index dielectric nanoparticles supporting a distinct series of Mie resonances have enabled a new class of optical antennas with unprecedented functionalities. Active control of higher-order anapoles and multimodal tuning are 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. The intention to control and manipulate light by fully exploiting the advantages from scattering resonances, at the nanometer scale, has stimulated the emergence of modern nanophotonics[3] and spawned a myriad of applications ranging from biochemistry to information technology[4] In this context, low-loss, high-index dielectric or semiconductor nanostructures featuring a diverse set of optical resonances are currently in the spotlight of research as they can serve as versatile and CMOS-compatible building blocks for various photonic devices[5,6,7,8,9]. By discovering the concealed portfolio of actively controllable resonances in GST nanostructures, our findings establish a new basis for designing active optical components and pave the way towards metadevices with tunability on demand[58]

Methods

Results

Conclusion