Ge 2 Sb 2 Te 5 -enabled nonvolatile switching of symmetry-engineered chiral q-BIC states in mid-infrared metasurfaces
Year: 2026
Type: article
Abstract: Nonvolatile control of chiral quasi-bound states in the continuum (q-BICs) is desirable for reconfigurable mid-infrared polarization devices. We propose a Ge 2 Sb 2 Te 5 (GST) metasurface in which a symmetry-protected parent BIC is converted into extrinsic and intrinsic planar chiral q-BICs through oblique illumination and in-plane geometrical asymmetry, respectively. The extrinsic pathway yields near-unity CD and CCD, whereas the intrinsic pathway produces CD of approximately 0.8 with CCD approaching unity, through selective enhancement of distinct cross-circular polarization-conversion channels. Crystallizing GST suppresses both responses by resonance detuning and absorption-induced Q-factor degradation, producing modulation depths approaching 100% at the amorphous-state operating wavelengths. These results provide a strategy for nonvolatile circular-polarization control and integrated chiral photonics.
Source: Optics Express
DOI: 10.1364/oe.613467
Institution: Changchun University of Science and Technology
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,270
OpenAlex ID: W7221013517