arXiv subjects

Junke Liao

Publications and source records attributed to Junke Liao.

4 recordsLinked to original sources

arXiv2026

Torus-Projected Electromagnetic Wormholes Enabled by Anisotropic Singularity Reconstruction of Metamaterials

Transformation optics uses coordinate mappings to emulate curved geometries and control electromagnetic fields. However, existing approaches primarily focus on geometric deformation while offering limited control over the global topology of the resulting optical space. Here we introduce a torus projection combined with a conformal mapping to construct a wormhole-like virtual optical geometry, providing a controllable route to manipulate virtual space topology within transformation optics. By tuning a single torus parameter, the virtual-space refractive index switches between isotropic and anisotropic forms, driving a transition from a disconnected horn-torus geometry to a connected ring-torus geometry in virtual space. In physical space, this virtual-space topology transition gives rise to switchable black-hole-like trapping, field redistribution, and geometry-controlled wave responses. Our results demonstrate how refractive-index anisotropy governs singularity structure and topology in transformation optics, while also suggesting practical functionalities including beam splitting, absorbing-like switching, and curvature-assisted focusing.

physics.optics↗

arXiv2025

Hyperbolic Continuous Topological Transition in Real Space

Hyperbolic topological transitions refer to the transformation of is isofrequency contours in hyperbolic materials from one topology (e.g., hyperbolic) to another (e.g., elliptical or a different hyperbolic topology). However, current research remains limited to investigating topological transitions in momentum space, thereby hindering the simultaneous real-space observation of distinct hyperbolic states and their associated topological transitions within a single system. In this work, we investigate real-space hyperbolic continuous topological transitions using gradient-index (GRIN) lenses, exemplified by hyperbolic Luneburg lens. By introducing Wick rotations, we demonstrate how spatially modulated refractive indices, mediated by variations in out-of-plane permittivity, drive continuous transitions between hyperbolic Type I and Type II topologies. Furthermore, using a harmonic oscillator model, we uncover the intrinsic relationship between the parameter E of hyperbolic Luneburg lens and its predominant topological behavior, whether hyperbolic Type I or Type II, and extend this concept to a broader framework of Morse lenses. This work provides a theoretical foundation for designing materials with tunable topological properties, advancing applications in photonics, metamaterials, and beyond.

physics.optics↗

arXiv2025

Double Negative Metamaterials in Water Waves

Water waves present both opportunities and hazards, which demand precise control to effectively exploit their energy and mitigate their destructive effects. Leveraging the unique propagation characteristic of negative refraction enables versatile strategies for achieving such control. Here, we propose a Veselago-Pendry double negative metamaterial (DNM) for water waves constructed by nested gears and split tubes. This uniform array structure realizes effective negative water depth and gravity distributions, enabling tunable negative refraction that resolves the unclear structure-propagation relationships and stringent layout requirements of prior negative refraction structures. By employing coherent potential approximation (CPA), negative effective water depth ue and gravity ge are predicted. The predicted DNM parameters align well with band structures, and are validated by simulations of isolation, wave bending and all-angle imaging with surface waves excitation. A simplified experiment demonstrating water wave bending was successfully performed, matching the analytical predictions and simulation results well. Through quantitative mapping between structural parameters and propagation properties that enables tunable bandgaps and controllable negative refraction, DNMs furnish a transformative toolkit for coastal engineering, and are able to calm harbors, boost wave-energy harvesters, and steer river-bend currents to curb erosion.

physics.app-ph↗

arXiv2023

Mirrored Transformation Optics

A mirrored transformation optics (MTO) approach is presented to overcome the material mismatch in transformation optics. It makes good use of the reflection behavior and introduce a mirrored medium to offset the phase discontinuities. Using this approach, a high-performance planar focusing lens of transmission-type is designed, which has large concentration ratio than other focusing lens obtained by generalized Snell law. The MTO will not change any functionality of the original lens and promising potential applications in imaging and light energy harvesting.

physics.optics↗