arXiv subjects

Abdullah F. Alharbi

Publications and source records attributed to Abdullah F. Alharbi.

3 recordsLinked to original sources

arXiv2026

Dual-Symmetrized Construction of Electromagnetic Beams Beyond the Paraxial Approximation with an Explicit Separation of Scalar and Vectorial Corrections

We develop a perturbative framework for constructing the fields of electromagnetic beams beyond the paraxial approximation, in which the vectorial correction is shared symmetrically between the electric and magnetic fields and separated from the isotropic scalar correction. The method is based on a direct iterative derivation from Maxwell equations and combines complementary electric-first and magnetic-first constructions, thereby removing the construction-dependent assignment of the vectorial correction to either the electric or magnetic field. In addition, the scalar envelope correction is obtained independently from the isotropic co-polar contribution to the solutions of the higher-order Helmholtz equation. The resulting corrected fields apply to an arbitrary paraxial envelope and input Jones polarization.

physics.optics↗

arXiv2026

Transversality Locks Longitudinal Gradients in Structured-Light Quadrupole Transitions

Electric quadrupole absorption is driven by optical field gradients, not by field amplitudes alone. This distinction is crucial for structured light, where a paraxially small longitudinal field can generate a leading-order longitudinal gradient. For fully vectorial Laguerre-Gaussian modes, Maxwell transversality locks this longitudinal gradient to the transverse structured gradient of the leading paraxial field. This locking is therefore a general electromagnetic constraint, not a focusing-dependent correction that can be removed independently. Decomposing the symmetric-traceless optical field-gradient tensor into spherical components reveals a strongly channel-selective response: the $Δm=0$ transition requires the longitudinal gradient at the retained order, the $Δm=\pm1$ channels receive scalar and vectorial nonparaxial corrections on top of the carrier-scale longitudinal derivative of the transverse field, and the $Δm=\pm2$ channels remain transverse at the same order. These results show that longitudinal optical structure can enter structured-light quadrupole transitions as an indispensable leading-gradient contribution, even when the longitudinal field amplitude itself is paraxially small.

physics.optics↗

arXiv2022

Resonance effects in Brunel harmonic generation in thin film organic semiconductors

Organic semiconductors have attracted extensive attention due to their excellent optical and electronic properties. Here, we present an experimental and theoretical study of Brunel harmonic generation in two types of porphyrin thin films: tetraphenylporphyrin (TPP) and its organometallic complex derivative Zinc tetraphenylporphyrin (ZnTPP). Our results show that the $π$-$π^\ast$ excitation of the porphyrin ringsystem plays a major role in the harmonic generation process. We uncovered the contribution of an interband process to Brunel harmonic generation. In particular, the resonant ($S_0 \rightarrow S_2$ transition) enhanced multiphoton excitation is found to lead to an early onset of non-perturbative behavior for the 5th harmonic. Similar resonance effects are expected in Brunel harmonic generation with other organic materials.

physics.optics↗