arXiv subjects

J. Mulia-Rodriguez

Publications and source records attributed to J. Mulia-Rodriguez.

4 recordsLinked to original sources

arXiv2026

Achieving Extraordinary Acoustic Transmission in a Single Slit by Boundary Impedance Engineering

Extraordinary acoustic transmission is commonly associated with periodic or multi-aperture structures. In this work, we show that a single subwavelength slit can support strongly enhanced transmission when its boundary response is described by an effective impedance. Using a reduced analytical model together with numerical calculations, we demonstrate that appropriate impedance tuning leads to efficient coupling between the incident field and the slit mode, resulting in transmission levels approaching unity. The observed enhancement is governed by impedance matching rather than geometric periodicity, highlighting a minimal mechanism for extraordinary transmission. This study establishes boundary impedance control as a versatile route for manipulating acoustic wave transport through deeply subwavelength apertures.

physics.optics↗

arXiv2025

Energetic vs Inference-Based Invisibility: Fisher-Information Analysis of Two-Layer Acoustic Near-Cloaks

Near-cloaks based on passive coatings can strongly suppress scattered-field energy in a narrow frequency band, yet an observer's ability to infer object parameters from noisy measurements need not decrease proportionally. We develop a fully theoretical two-dimensional (2D) framework for a coated acoustic cylinder in an air background. Using an exact cylindrical-harmonic solution of the Helmholtz equation, we compute the modal scattering coefficients a_m(omega) for a core of radius a surrounded by two concentric effective-fluid layers, and we design the coating to cancel the dominant low-order multipoles (monopole m=0 and dipole m=+/-1) at a target frequency, yielding a narrowband near-cloak. Beyond the conventional energetic metric (total scattering width), we quantify information-based detectability through the Fisher information matrix (FIM) and the associated Cramer-Rao lower bounds (CRLBs) for joint estimation of the size-material parameter vector x=[a, rho1, c1]^T from noisy far-field data. A representative air-background study exhibits an approximately 25 dB reduction in total scattering width near the design frequency, while tr(FIM) decreases by only a few dB, demonstrating that energy-based and inference-based notions of invisibility are distinct objectives. We further provide a low-order analytic argument clarifying the mechanism behind this energetic-informational decoupling and report design-space and local-robustness diagnostics that highlight persistent trade-offs between scattering suppression and parameter identifiability.

physics.optics↗

arXiv2025

Fisher Information as an Operational Metric for Structured Optical Beams

Structured optical beams possess rich spatial features that are commonly characterized using entropic measures of field complexity. However, such measures do not directly quantify the operational usefulness of optical structure for parameter estimation and sensing. Here we introduce Fisher information as an operational metric to assess the metrological content of structured optical fields. By treating the measured intensity distribution as a statistical object, we define Fisher information with respect to physically relevant parameters, such as transverse displacement. We demonstrate that optical modes with comparable Shannon entropy can exhibit markedly different Fisher information, revealing sensitivity features associated with nodal structure and local curvature. Using Hermite--Gaussian modes as minimal test cases, we show that increasing modal order systematically enhances Fisher information. We then extend the analysis to two widely used families in structured light: Laguerre--Gaussian vortex beams and finite-energy Bessel--Gauss beams. Across these representative families, Fisher information provides a unified and experimentally accessible criterion for comparing structured optical fields in sensing applications.

physics.optics↗

arXiv2025

Topological reorganization of near-field energy flow governing scattering transitions in subwavelength rectangular grooves

The scattering of electromagnetic waves by subwavelength rectangular grooves has been extensively studied, yet its physical interpretation has largely relied on field-intensity distributions. Here we demonstrate that the transition from concave to convex scattering profiles observed as the groove width approaches the wavelength is governed by a topological reorganization of the near-field energy flow. Using a rigorous modal formulation for TM-polarized fields, we analyze the complex electromagnetic field and the associated time-averaged Poynting vector. We show that reducing the groove width induces the creation, migration, and annihilation of Poynting-vector singularities, including vortices and saddle points, leading to a qualitative restructuring of electromagnetic energy transport. This topological transition redirects the local energy flux and manifests as a convex scattering profile in the far field. The results establish a direct link between near-field energy topology and far-field scattering, providing a unified physical interpretation of subwavelength groove scattering.

physics.optics↗