Optical Resonance Tuning of Single Polystyrene Microspheres Using the Phase-Change Material In3SbTe2 as a Switchable Mirror

Dielectric nanoparticles and microparticles show rich optical responses due to their electric and magnetic multipolar Mie modes and low losses. These optical resonances can be modified via the particle size, shape, and dielectric environment. Here we tune the infrared multipolar Mie resonances of dielectric polystyrene microspheres using the plasmonic phase-change material In3SbTe2 (IST). IST exhibits a phase change between a dielectric amorphous phase and a crystalline phase that is metallic in the infrared. We show that a reversibly switchable particle-on-mirror geometry can be created by locally switching the IST under the polystyrene microspheres. Measuring the light-scattering spectra of single polystyrene microspheres before and after crystallization and reamorphization, we observe huge shifts of the resonance wavelength, e.g., from 5.2 to 8.9 μm and back for 6 μm diameter spheres. Our work is a first step toward a controlled tuning of multipolar Mie modes of various particles using reprogrammable IST mirror structures.