Approaching High-efficiency Spatial Light Modulation with Lossy Phase-change Material

TL;DR

This paper presents a novel design strategy for high-efficiency spatial light modulation using lossy phase-change materials, optimizing the phase transition process to minimize absorption effects and enable multifunctional photonic control.

Contribution

The study introduces a design approach that exploits quasi-continuous phase transitions in PCMs, achieving high modulation efficiency and extending functionality to polarization control.

Findings

Minimum reflectance of 46.5% at 1550 nm

Phase modulation depth of 246.6 degrees

Effective polarization modulation through structural anisotropy

Abstract

The prevalent high intrinsic absorption in the crystalline state of phase-change materials (PCMs), typically leads to a decline in modulation efficiency for phase-change metasurfaces, underutilizing their potential for quasi-continuous phase-state tuning. This research introduces a concise design approach that maximizes the exploitation of the quasi-continuous phase transition properties of PCM, achieving high-efficiency spatial light modulation. By optimizing the metasurface design, the phase modulation process is strategically localized in a low crystallization ratio state, significantly reducing the impact of material absorption on modulation efficiency. Utilizing GSST as an example, numerical simulations demonstrate a minimum reflectance of 46.5% at the target wavelength of 1550 nm, with a phase modulation depth of 246.6{\deg}. The design is fruther extended to dynamic polarization modulation by incorporating structural anisotropy, enabling independent control of amplitude and phase modulation in orthogonal polarization directions. This strategy not only circumvents the efficiency limitations of crystalline states but also harnesses the full potential of PCMs for multifunctional photonic applications.