arXiv subjects

Anand Hegde

Publications and source records attributed to Anand Hegde.

4 recordsLinked to original sources

arXiv2026

Plasmonic Spin Meron Lattices with Height-Sensitive Topology Evolution

We demonstrate height-controlled topological switching of plasmonic spin meron lattices above a metallic square coupling structure under circularly polarized illumination. Near the interface, an evanescent surface plasmon polariton (SPP) channel yields a N\'eel-type meron lattice with $\pm\frac{1}{2}$ like effective site charges. At larger heights, diffracted fields from the square edges dominate and convert the lattice into a Bloch-type configuration. Over a range of intermediate heights, crossover between the evanescent SPP and edge diffraction gives rise to rich rapid topology evolutions. The switching is accompanied by nucleation of off-boundary vortex-anti vortex pairs in the in-plane spin phase, producing height-dependent fractional site charges. Our findings are analytically formulated by linear superposition of SPPs in the plasmonic regime and Stratton-Chu model in diffraction regime and confirmed via full-wave finite-difference time-domain simulations.

physics.optics↗

arXiv2025

Advancing Plasmonic Computing with Single-Beam Logic Primitives

Plasmonic logic circuits combine ultrafast operation with nanoscale integration, making them a strong candidate for next-generation optical computing. Realizing this potential, however, requires overcoming practical challenges such as bulky interferometric designs and reliance on secondary control signals. This work advances plasmonic logic by introducing a single-global threshold mechanism in plasmonic two-wire transmission lines, empowered with polarization modal selectivity and geometric tuning to enable versatile circuit functionality. The scheme embeds the control signal with a single laser beam, supporting six deterministic polarization states and eliminating the need for auxiliary inputs. With this framework, we experimentally demonstrate advanced logic operations, including a 2-bit comparator, parity checkers, and encoder/decoder circuits. The approach reduces circuit footprint by 67% and power consumption by 50% relative to state-of-the-art systems, while maintaining low latency and high stability. By unifying thresholding, polarization, and geometry into a compact, source-free scheme, this work pushes plasmonic nanocircuitry from device-level novelty toward scalable, energy-efficient architectures for next-generation optical processors.

physics.optics↗

arXiv2025

Phase Matched Plasmonic Transmission Lines for Cascaded Second-Harmonic Generation as a Pathway to Nonlinear Logic Circuits

In nonlinear nanophotonics, cascaded second-harmonic generation (SHG) in pure plasmonic waveguides for sequential signal transformation and complex on-chip functionality remains a long-standing challenge. Precise phase matching becomes instrumental to achieve efficient SHG and enable true cascading of nonlinear processes. We experimentally demonstrate phase matching in SHG is achievable in a plasmonic system between two orthogonal modes. Accurate tuning of plasmonic two-wire transmission-line (TWTL) design parameters result in SHG from the antisymmetric excitation mode being approximately 15 times stronger than that from the symmetric excitation mode, greatly raising the conversion efficiency to 0.021%. Simultaneously, phase matching extends our TWTL operational length up to 18${\mu}$m. Based on the improved efficiency and operational length, we demonstrate the feasibility of cascading multiple plasmonic waveguides. We further realize a nonlinear AND logic operation using a single 18${\mu}$m long waveguide. These results underscore the potential of phase matched plasmonic TWTLs for compact, efficient, and scalable nonlinear optical circuitry.

physics.optics↗

arXiv2025

Geometry-Driven Lattice of Photonic Spin-Meron Tubes in Free Space

We theoretically demonstrate the first photonic spin-meron tube lattice in free space using spin-angular momentum vectors. Square-block diffraction creates $C_{4}$-symmetric beams with $\pi/2$ phase steps. Non-paraxial spin-orbit coupling then forms finite-length meron tubes ($N_{\mathrm{sk}} \approx \pm 1/2$, $> 25,\lambda$). Extending the formalism, we show that $C_{3}$ geometry of a triangular block yields a spin-skyrmion tube. Stratton-Chu theory and full-vectorial finite-difference time-domain calculations both support this material-agnostic, geometry-driven approach as a platform to explore symmetry-driven free-space topology.

physics.optics↗