Nanopatterning of Phase-Change Material Thin Films For Tunable Photonics

Abstract

For manipulation of light’s amplitude, phase and polarization, metasurfaces arose as promising candidates with capabilities beyond those of classical optical components. Once fabricated, however, metasurfaces have set optical properties and are thus passive . Active metasurfaces are made out of nanostructures whose optical properties can be externally manipulated. 1 To tune e.g . the optical environment of the nanostructures, phase-change materials (PCMs) became popular due to their high optical contrast and non-volatility. PCMs have been employed as surrounding medium for plasmonic resonators and studies employing PCMs as all-dielectric metasurfaces are promising. The switching of PCMs by optical means lead to successful patterning in the µm-regime. 2 Bypassing the limits of diffraction imposed by optical switching, we employ a powerful thermal scanning probe lithography (t-SPL) technique to control position, depth and size of the switched PCM. First theoretical studies and metasurface designs for metasurfaces enabled by t-SPL could have exciting applications in the near infrared spectral range. 3