Active control of amorphous and crystalline GSST multilayer layouts in a 1D gold grating through thermoplasmonic induced process

Abstract

Chalcogenide phase-change materials (PCMs) are particularly suited for dynamically controlling the response of photonic devices because they offer high-speed phase switching, non-volatility, reversibility, high thermal stability, and multi-level structure capability. Ge2Sb2Se4Te1 (GSST) has recently received intense attention due to the remarkable differences between the optical and electrical features of its two states (amorphous and crystalline). The crystallization is rapid with significantly low optical loss across the visible and near-infrared spectral ranges. In this paper, we propose a reconfigurable one-dimension (1D) gold Fabry-Perot grating filled with GSST irradiated by a nanosecond Gaussian pulse laser. By using the finite element method (FEM), we calculate the dynamics of partially crystallized GSST through a thermoplasmonic induced process. Our results show that with well-chosen pulse laser fluences, we can achieve a different layout of alternating amorphous and crystalline GSST states in the grating grooves where all the structural variations remain constant. These induced multi-layered formations in the grating grooves results in a tunable light absorber nanostructure where the absorption peaks experience a red shift gradually decreasing in value as the number of layers is increased. The findings of this study not only provide the fundamental concepts for the suggested tunable nanostructure but also suggest potential applications in various nanophotonic devices including thermal emission controllers, multi-level memories, color displays, and cognitive computing devices.