Nonvolatile, reconfigurable and narrowband mid-infrared filter based on surface lattice resonance in phase-change GeSbTe

TL;DR

This paper introduces a nonvolatile, reconfigurable mid-infrared filter using surface lattice resonance in phase-change GeSbTe, tunable via phase transition and design parameters, with potential applications in reconfigurable optics.

Contribution

The work demonstrates a novel GST-based surface lattice resonance filter with tunable spectral properties and adjustable Q-factors, advancing nonvolatile reconfigurable mid-infrared filtering technology.

Findings

Spectral tuning from 3.197 μm to 4.795 μm with phase change

Q-factor adjustable from 10.3 to 70 by design

Peak reflection efficiency up to 80% with trade-offs

Abstract

We propose a nonvolatile, reconfigurable, and narrowband mid-infrared bandpass filter based on surface lattice resonance in phase-change material Ge2Sb2Te5 (GST). The proposed filter is composed of a two-dimensional gold nanorod array embedded in a thick GST film. Results show that when GST transits from the amorphous state to the crystalline state, the narrowband reflection spectrum of the proposed filter is tuned from 3.197 {\mu}m to 4.795 {\mu}m, covering the majority of the mid-infrared regime, the peak reflectance decreases from 72.6% to 25.8%, and the corresponding Q-factor decreases from 19.6 to 10.3. We show that the spectral tuning range can be adjusted by varying the incidence angle or the lattice period. By properly designing the gold nanorod sizes, we also show that the Q-factor can be greatly increased to 70 at the cost of relatively smaller peak reflection efficiencies, and that the peak reflection efficiency can be further increased to 80% at the cost of relatively smaller Q-factors. We expect this work will advance the engineering of GST-based nonvalatile tunable surface lattice resonances and will promote their applications especially in reconfigurable narrowband filters.