Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2504.04432

A sectorial arrangement of spatially-shifted grating for composite Laguerre-Gaussian OAM beam generation

Pratyush Pushkar·Nirjhar Kumar
View original source ↗Read source document ↗Export metadata ↓

Abstract

The first diffraction order of a planar 1D grating has a plane wavefront for a plane wave incidence. We propose an algorithm to tailor the shape of this wavefront to the desired propagation mode. The algorithm works by segmenting the 1D grating into sectors and shifting gratings in each sector along the grating vector by some fraction of the grating period. The algorithm determines the fractional shift required in each sector to impart a desired shape to the wavefront. Through simulations and experiments, we show the applicability of the design process by demonstrating the coaxial generation of one or multiple Laguerre-Gaussian orbital angular momentum beams. In addition, we demonstrate the independent regulation of relative intensities and phases of components in the generated beam.

Explore related subjects

physics.optics

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Pratyush Pushkar, Nirjhar Kumar. 2025-04-06. A sectorial arrangement of spatially-shifted grating for composite Laguerre-Gaussian OAM beam generation. https://arxiv.org/abs/2504.04432

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

KEEP EXPLORING

Related papers

arXiv2026

Nonlinear Magneto-Optical Probing of Time-Reversal Symmetry Breaking

Solid-state harmonic generation provides a nonlinear probe of symmetries encoded in electronic wave functions. In the subgap and weak-injection regime, time reversal pairs the harmonic responses driven by fields of opposite ellipticity, strongly suppressing elliptical dichroism in time-reversal-symmetric crystals. We show that, in a magnetic crystal, spin-orbit coupling transfers time-reversal-symmetry breaking from the spin sector to the orbital wave functions and lifts this pairing through the geometric phases of the electric-dipole current. Semiconductor-Bloch-equation calculations for centrosymmetric bilayer Cr2Ge2Te6 predict pronounced third-harmonic elliptical dichroism that reverses with the magnetization. Under linearly polarized driving, SOC-induced geometric-phase accumulation generates a nonlinear transverse current and strongly enhances the harmonic rotation and ellipticity. These results identify the geometric phase as a key microscopic contribution to the nonlinear magneto-optical response. This work establishes helicity-resolved harmonic emission and nonlinear polarimetry as complementary probes of spin-orbit-coupled magnetic order.

physics.optics↗
arXiv2026

Spatiotemporal topological phase transitions in photonic spacetime crystals

Topological phase transitions have played a central role in topological physics. However, such transitions have so far been restricted to spatial or temporal crystals. Here, we transcend this conventional framework and report, for the first time, spatiotemporal topological phase transitions in photonic spacetime crystals - structures that are periodically modulated in both space and time. In a genuine photonic spacetime crystal composed of a dynamically modulated transmission-line metamaterial, we theoretically propose and experimentally demonstrate complete spatiotemporal topological phase transitions, characterized by the closing and reopening of both energy and momentum band gaps, along with changes in spatiotemporal topological invariants and topological phases. Furthermore, we directly observe a spatiotemporal, topologically localized state that exhibits causality-governed excitation and robustness to spatiotemporal disorders. Our findings reveal the interplay among space, time, and topology, establishing a unified framework that provides a comprehensive picture of the emerging topological spacetime physics and opening new avenues for robust spatiotemporal topological wave manipulations.

physics.optics↗
arXiv2026

High-Resolution Sensing via Quantum States Discrimination

High-resolution sensing plays a significant role in scientific research and industrial production, but the practical implementation is constrained by the physical mechanisms of the sensors. To address the critical limitation, we propose a high-resolution sensing approach based on quantum state discrimination. Distinct from conventional strategies, the proposed approach constructs measurement operators in the orthogonal complement space rather than eigenspace of the eigenstate, thereby notably improving the discriminability among quantum states. Moreover, the experimental results via an optical microcavity demonstrate a potential sensing resolution of 4 $\times$ 10\textsuperscript{-6} \degree C and 18 p$ε$ respectively for temperature and strain, and further verify the feasibility of simultaneous sensing of the two parameters. This work establishs a universal approach for high-resolution sensing, and may be extended to different sensing platforms across various application scenarios.

physics.optics↗