title: Reversible optical switching of highly confined phonon-polaritons with an ultrathin phase-change material.
abstract: Surface phonon-polaritons (SPhPs), collective excitations of photons coupled with phonons in polar crystals, enable strong light-matter interaction and numerous infrared nanophotonic applications. However, as the lattice vibrations are determined by the crystal structure, the dynamical control of SPhPs remains challenging. Here, we realize the all-optical, non-volatile, and reversible switching of SPhPs by controlling the structural phase of a phase-change material (PCM) employed as a switchable dielectric environment. We experimentally demonstrate optical switching of an ultrathin PCM film (down to 7 nm, <λ/1,200) with single laser pulses and detect ultra-confined SPhPs (polariton wavevector kp > 70k0, k0 = 2π/λ) in quartz. Our proof of concept allows the preparation of all-dielectric, rewritable SPhP resonators without the need for complex fabrication methods. With optimized materials and parallelized optical addressing we foresee application potential for switchable infrared nanophotonic elements, for example, imaging elements such as superlenses and hyperlenses, as well as reconfigurable metasurfaces and sensors.
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Peining
authors.initials: P
authors.lastname: Li
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: Yang
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Tobias W W
authors.identifier: 0000-0003-1498-1025
authors.initials: TW
authors.lastname: Maß
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Hanss
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Lewin
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Ann-Katrin U
authors.initials: AK
authors.lastname: Michel
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wuttig
authors.affiliation: Institute of Physics (IA), RWTH Aachen University, Aachen 52056, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Taubner