Projeto e análise óptica de estruturas de filtro-absorvedor reconfiguráveis integradas com materiais de mudança de fase

Abstract

Phase‐change materials (PCMs) based on chalcogenides have emerged as promising functional platforms due to their unique ability to combine state retention, an essential feature for non-volatile memory applications, with pronounced contrasts in electrical and optical properties between the amorphous and crystalline phases. Over the past decade, these materials have been extensively explored in optics and photonics, driven by their high refractive-index contrast, non-volatility, and compatibility with integration processes on established photonic platforms. This thesis presents the development, modeling, and analysis of reconfigurable photonic devices based on PCMs. The proposed work investigates the use of GeTe, In3SbTe2 (IST), and Sb2S3 in active and tunable optical applications, taking advantage of their distinctive optical properties that enable dynamic spectral modulation through reversible phase transitions. Such transitions allow active control over the absorption, reflection, and transmission of electromagnetic radiation. The developed architectures include planar and multilayer nanoscale configurations, with emphasis on ultrathin optical absorbers and filters. The analyses were performed through numerical simulations based on the Finite Element Method (FEM), incorporating realistic, wavelength-dependent dispersive models. For Sb2S3 in particular, experimental studies were also carried out, involving the nanofabrication of thin films via physical vapor deposition (PVD) and spectroscopic ellipsometry characterization conducted at École Centrale de Lyon (France). From these measurements, complex optical parameters were extracted for both phase states, showing excellent agreement with the simulated results, thereby validating both the developed optical model and the suitability of Sb2S3 for actively controlled photonic devices. The results demonstrate the strong potential of PCMs for enabling reconfigurable photonic architectures aimed at spectral modulation, optical sensing, and communication applications. The proposed devices were designed to operate from the visible to the mid-infrared spectral ranges, exploiting different physical mechanisms associated with electromagnetic field interaction and confinement, including resonance effects, interference, and optical coupling. Finally, the influences of geometric and material parameters on device performance are analyzed, along with the feasibility of nanoscale fabrication. These findings highlight the relevance of PCMs for next-generation integrated photonics and programmable optoelectronic technologies.