Experimental demonstration of Ge2Sb2Te5 loaded 1-D plasmonic metasurface perfect absorber for near-IR wavelength regime

Abstract

Inclusion of a phase change material such as germanium–antimony–telluride (Ge2Sb2Te5 or GST) enhances the performance of plasmonic metasurface absorbers (PMAs). One-dimensional (1-D) plasmonic metasurfaces (PMs) support the excitation of surface plasmon modes for the normal incidence of transverse magnetically (TM) polarized light. The 1-D PMAs absorb incident light because of their confinement in the groove region, which is possible because of the surface plasmon modes excited at the metal–dielectric interface. A thin layer of the phase change material enhances the absorption of incident light because of the increasing strength of the confined electromagnetic field in the vicinity of the PMA. We developed a GST loaded, low cost, 1-D PMA for the absorption of near-infrared (NIR) light (740–920 nm). The PMA was fabricated using an Ag coated 1-D patterned polycarbonate, which was obtained from a commercial digital versatile disk (DVD). A 1-D PMA of 1 cm2 in size obtained from a DVD was coated with a GST layer of 8 nm in thickness to achieve the maximum absorption of 99.56% for the hexagonal closed packed (h.c.p.) crystalline state of the GST loaded layer. Control experiments were performed for different temperatures and different thicknesses of the GST layer for achieving an optimal performance nearing perfect absorption. Electric and magnetic field profiles were simulated for the normal incidence of TM-polarized light to understand the underlying physics of the light–matter interaction with the PMA. Such a PMA can be used to develop various cost-effective optical devices, such as optical sensors, optical filters, photodetectors, and heat absorbing photonic windows in the NIR wavelength regime.