arXiv subjects

Zhonglin Li

Publications and source records attributed to Zhonglin Li.

4 recordsLinked to original sources

arXiv2026

Phase singularity enabled polarization switchable analog spatial differentiation in an atomic MoS$_2$ planar Fabry-Pérot cavity

Reconfigurable analog optical computing requires rapid and efficient switching between core mathematical operations, such as first- and second-order spatial differentiation. Here, we demonstrate a monolayer MoS$_2$ integrated a planar Fabry-Pérot (F-P) cavity that performs polarization switchable analog spatial differentiation under oblique incidence. By exploiting polarization dependent phase singularities, the device satisfies distinct optical transfer functions for different-order differentiation at the same operating condition. As a result, first-order and second-order derivatives of input images are experimentally realized by simply switching the incident polarization. These results establish the planar cavity as a compact reconfigurable spatial differentiator, whose computational order is controlled solely by light polarization. This approach provides a fast, convenient, and integration friendly strategy for tunable optical computing, and enables polarization switchable edge detection for image processing, with potential applications in real-time object recognition, feature extraction, and optical data compression.

physics.optics↗

arXiv2025

Guiding polaritonic energy and momentum through two-dimensional Bravais lattices

The strong exciton absorption in monolayer transition metal dichalcogenides provides a promising platform for studying polaritons with tunable dispersions, which are crucial for controlling polaritonic energy and momentum, but remain underexplored. In this work, monolayer MoS$_2$ is coupled with a Fabry-Pérot microcavity to form polaritons. Five types of Bravais lattices with sub-wavelength periods, based on polymethyl methacrylate (PMMA) nanopillars, are intentionally designed. The energy overlap between the periodic PMMA scattering wave and the polariton establishes a coupling channel that controls the directional flow of polaritonic energy, as demonstrated through angle-resolved reflectance measurements. Back-space image measurements further demonstrate that the dispersion in reciprocal space can be directly and manually tuned, allowing for control over their number and their positions. The coupling between the polariton and PMMA scattering wave is further demonstrated by analyzing the reflectance using the two-port two-mode model. The symmetries of 2D Bravais lattices allow the angle between energy and momentum flow to vary widely, from 90°, 60°, 45°, and 30° to arbitrary values. By adjusting the lattice vector lengths, the position of the dispersion branch in a specific direction can be fine-tuned, enabling full-range control over polariton dispersion. This work presents the first theoretical and experimental demonstrations of guiding the direction of polaritonic energy and momentum through Bravais lattice design.

physics.optics↗

arXiv2025

Fabry-Perot resonance modes in a MoS$_2$-based vertical stacking cavity for strong light-matter coupling and topological phase singularity

Rich dielectric properties in atomic transition metal dichalcogenides (TMDs) enhance light-matter interactions and contribute to a variety of optical phenomena. The direct transfer of TMDs onto photonic crystals facilitates optical field confinement and modifies photon dispersion through the generation of polaritons. However, light-matter interaction is severely limited by this stacking method. This limitation can be significantly improved by constructing a vertical stacking cavity with alternating layers of dielectric material and monolayer MoS$_2$. This multilayer structure is proven to be a compact, versatile, and customizable platform for controlling Fabry-Perot cavity resonance mode. Angle-resolved reflectance further aids in studying resonance mode dispersion. Moreover, the strong light-matter interaction results in multiple perfect absorptions, with the monolayer MoS$_2$ significantly contributing to the absorption in this system, as schematically revealed by the electric field distribution. The multiple perfect absorptions produce an unusual amounts of phase singularities with topological pairs, whose generation, evolution, and annihilation can be controlled by adjusting cavity parameters. Our findings provide a flexible and consistent framework for optimizing light-matter interactions and supporting further studies on wavefront shaping, optical vortices, and topological variants.

physics.optics↗

arXiv2024

Extremely long transverse optical needle focus for reflective metalens enabled by monolayer MoS$_2$

Line-scan mode facilitates fast-speed and high-throughput imaging with developing a suitable optical transverse needle focus. Metasurface with periodic structures such as diffractive rings, ellipses, and gratings could enable discrete focus evolving into line focus under momentum conservation, but still face the challenge of extremely low light power utilization brought by inevitably multiple high-order diffractions. In addition, the designed focus requires the selection of particular optical functional materials. High dielectric constants in atomic transition metal dichalcogenides make significant phase modulation by bringing phase singularity at zero-reflection possible. However, no light power is available for use at zero-reflection and a balance between phase and amplitude modulation is needed. In this work, above issues are simultaneously solved by designing a monolayer MoS2 based Fresnel strip structure. An optical needle primary focus with a transverse length of 40 μm (~80 λ) is obtained, which is the longest value recorded so far, together with a sub-diffraction-limited lateral spot and a broad working wavelength range. This specially developed structure not only concentrates light power in primary diffraction by breaking restriction of momentum conservation, but also guarantees a consistent phase across different strips. The novel optical manipulation way provided here together with the longer focus length for flat optics will show promising applications in biology, oncology, nanofabrication, energy harvesting, and optical information processing.

physics.optics↗