arXiv subjects

Aleksandra Deeva

Publications and source records attributed to Aleksandra Deeva.

2 recordsLinked to original sources

arXiv2024

Mid-IR chirality and chiral thermal emission through twisting

Chirality in the mid-infrared spectral range plays a crucial role across physical, chemical, and biological sciences, yet sources of chiral infrared light do not currently exist. Their development, using principles from the mature field of metamaterials, requires complex three-dimensional architectures that call for high-resolution lithography. We leverage the natural optical anisotropy found in several van der Waals crystals, for example $\alpha$-MoO$_3$, to demonstrate experimentally that its twisted bilayers break inversion-rotation symmetry and are thereby intrinsically chiral. Via direct thermal emission measurements of microscopic twisted bilayers, we demonstrate that these heterostructures generate chiral light through incandescence. Twisted configurations of van der Waals materials do not require any lithography, and offer a platform for large-scale chiral filters and thermal sources beyond conventional meta-architectures.

physics.optics↗

arXiv2023

Deep-subwavelength Phase Retarders at Mid-Infrared Frequencies with van der Waals Flakes

Phase retardation is a cornerstone of modern optics, yet, at mid-infrared (mid-IR) frequencies, it remains a major challenge due to the scarcity of simultaneously transparent and birefringent crystals. Most materials resonantly absorb due to lattice vibrations occurring at mid-IR frequencies, and natural birefringence is weak, calling for hundreds of microns to millimeters-thick phase retarders for sufficient polarization rotation. We demonstrate mid-IR phase retardation with flakes of $α$-molybdenum trioxide ($α$-MoO$_3$) that are more than ten times thinner than the operational wavelength, achieving 90 degrees polarization rotation within one micrometer of material. We report conversion ratios above 50% in reflection and transmission mode, and wavelength tunability by several micrometers. Our results showcase that exfoliated flakes of low-dimensional crystals can serve as a platform for mid-IR miniaturized integrated polarization control.

physics.optics↗