Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2511.19541

Designing Space-Time Metamaterials: The Central Role of Dispersion Engineering

Sajjad Taravati
View original source ↗Read source document ↗Export metadata ↓

Abstract

Space-time metamaterials are redefining wave engineering by enabling fully dynamic four-dimensional control of electromagnetic fields, allowing simultaneous manipulation of frequency, amplitude, momentum, and propagation direction. This unified functionality moves well beyond reciprocity-breaking mechanisms, marking a fundamental transition from static media to polychromatic, energy-efficient wave processors. This article establishes dispersion engineering as the core design paradigm for these dynamic systems. We show that the dispersion relation, linking frequency and wavenumber, serves as a master blueprint governing exotic wave phenomena such as nonreciprocity, beam splitting, asymmetric frequency conversion, amplification, spatial decomposition, and momentum bandgaps. By analyzing analytical dispersion surfaces and isofrequency contours in subluminal, luminal, and superluminal modulation regimes, we reveal how tailored spatiotemporal modulation orchestrates controlled energy flow among harmonic modes. We further demonstrate how this framework directly informs practical device operation, highlighting advanced implementations including angular-frequency beam multiplexing in superconducting Josephson junction arrays. Combining insights from wave theory, numerical modeling, and experimental realization, this work provides a comprehensive roadmap for leveraging dispersion engineering to design next-generation metamaterials for wireless communication, quantum technologies, and integrated photonics.

Explore related subjects

physics.opticsphysics.app-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Sajjad Taravati. 2025-11-24. Designing Space-Time Metamaterials: The Central Role of Dispersion Engineering. https://arxiv.org/abs/2511.19541

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Geometric Phases and Holonomy in Structured Optical Fields

Geometric phases are widely used in modern optics, yet their meaning and underlying geometry depend on the actual physical settings, which can substantially differ from one another. This tutorial article introduces geometric phases in nanophotonic systems, focusing on the interaction of structured light with nanostructures or metaatoms. We compare the present setting with conventional geometric phases of structured-light optics and show that similar phase laws may correspond to genuinely different underlying geometries. Our aim is to provide a pedagogical bridge between the mathematical language of geometric phases and experimentally relevant examples from nanophotonics.

physics.optics↗
arXiv2026

Induced Directional Switching of Platicon Microcombs in Photonic Crystal Ring Resonators

Microcombs in normal-dispersion photonic crystal ring resonators (PhCRs) are versatile building blocks for next-generation integrated photonic circuits, but their inherent backward-propagation bias necessitates optical circulators or complex filtering for comb extraction, creating a significant bottleneck for full on-chip integration and precluding self-injection locking schemes. In this work, we introduce Side-mode Induced Forward Forcing (SIFF), a robust method to control and reverse this directionality. By engineering auxiliary mode splittings on resonances adjacent to the pump, we steer the nonlinear dynamics to favor stable, forward-propagating platicon states. We identify an optimal coupling condition that ensures forward-comb dominance across a wide parameter range. Our findings, validated numerically and experimentally, enable circulator-free, integrated normal-dispersion microcombs compatible with self-injection locking, offering a scalable architecture for compact telecommunications and sensing systems.

physics.optics↗
arXiv2026

Programmable Intrinsic Circularly Polarized Emission

Circularly polarized luminescence (CPL) is central to chiral photonics, yet programming circularly polarized emission at the nanoscale remains challenging. Here, we program intrinsic CPL at its microscopic origin in laser-written all-inorganic perovskite nanocrystals embedded in glass. High-resolution transmission electron microscopy reveals a core-shell-like variation in interplanar spacing associated with intrinsic CPL, consistent with torsional lattice distortion. The torsional lattice distortion breaks inversion symmetry, while density functional theory calculations show that it lifts the spin degeneracy of the band-edge electronic states. Power-dependent measurements further reveal a transition from birefringence-mediated circular polarization to intrinsic CPL, accompanied by the emergence of a distinct core-shell-like lattice distortion in the nanocrystals. By tuning the incident linear polarization angle and focal depth, we deterministically control both the handedness and magnitude of the intrinsic CPL, with |glum| of approximately 4 ^ 10^-3. These results show that programmable intrinsic CPL originates from the structural and electronic properties of the emitting nanocrystals, enabling circularly polarized emission to be controlled at its microscopic origin and spatially encoded within a monolithic material.

physics.optics↗