arXiv subjects

Rafael F. Barros

Publications and source records attributed to Rafael F. Barros.

4 recordsLinked to original sources

arXiv2026

A Collective Propagation Law of Optical Vortex Constellations and Longitudinal Sensing

Optical vortices are ubiquitous phenomena naturally appearing in wave physics, yet higher-order charges inherently split into constellations of lowest-order singularities at the smallest deviation from an ideal situation. While these constellations are common phenomena in real-world scenarios, characterizing their longitudinal evolution typically relies on exhaustive full-field descriptions or the ambiguous, sequential tracking of individual singularities. Here, we reveal and experimentally demonstrate a simple deterministic law describing the paraxial longitudinal propagation of an arbitrary constellation of optical vortices in standard Gaussian backgrounds. By mapping the constituting singularity coordinates to their elementary symmetric polynomials (ESPs), we capture the holistic evolution of the constellation during propagation, completely bypassing the practical need to sequentially track indistinguishable vortices. We further show that such complex ESPs provide a useful metrological tool for the estimation of longitudinal displacements. Our results reveal a previously unrecognized compact description of collective vortex dynamics, introducing a new route to longitudinal sensing through singularimetry.

physics.optics↗

arXiv2026

Spontaneous parametric down-conversion pumped by spatiotemporal structured light

Here we investigate the all-optical control of spectral correlations in spontaneous parametric down-conversion. We show that when photon pairs are projected onto high-order spatial modes, the spatial structure of the pump field defines the phase-matching function of the nonlinear interaction. Thus, by structuring the pump field in both space and spectrum, the biphoton spectral correlations are fully controlled. Considering a standard periodically-poled crystal as the nonlinear medium, we show that the Gouy phase matching method proposed here can generate both spectrally uncorrelated and high-dimensional spectrally entangled photon pairs, similarly to what is achieved with aperiodically-poled crystals. Furthermore, we show that our method can generate a wider class of quantum states if the pump field is a spatiotemporal wavepacket, that is, if its spatial and spectral structures are correlated.

quant-ph↗

arXiv2025

Power-Scalable Generation of High-Order Optical Vortices Via Coherent Beam Combining

Structured light beams, such as optical vortices carrying orbital angular momentum, are essential for applications ranging from low-power optical communications to high-intensity laser-matter interactions. However, scaling their power and energy while preserving complex phase and spatial structures remains a fundamental challenge. In this work, we demonstrate coherent beam combining as a versatile and scalable method for generating high-power structured beams without limitations on topological charge or spatial structure, while maintaining exceptionally high modal purity. We experimentally implement coherent beam combining for optical vortex beams with topological charges l = 1, 5, and 8, achieving a combined average power of 100 W and a peak power of 100 kW, with combining efficiencies of 95.0%, 93.9%, and 91.2%, respectively. Off-axis digital holography confirms that the phase and intensity profiles of the combined beams retain high modal purity, even at high topological charges. These results establish coherent beam combining as an effective route to high modal purity structured light at high power levels, unlocking new opportunities for advanced photonics and high-intensity light-matter interaction studies.

physics.optics↗

arXiv2022

Observation of the quantum Gouy phase

Controlling the evolution of a photonic quantum states is crucial for most quantum information processing and metrology tasks. Because of its importance, many mechanisms of quantum state evolution have been tested in detail and are well understood. However, the fundamental phase anomaly of evolving waves called the Gouy phase has not been studied in the context of elementary quantum states of light such as photon number states. Here we outline a simple method for calculating the quantum state evolution upon propagation and demonstrate experimentally how this quantum Gouy phase affects two-photon quantum states. Our results show that the increased phase sensitivity of multi-photon states also extends to this fundamental phase anomaly and has to be taken into account to fully understand the state evolution. We further demonstrate how the Gouy phase can be used as a tool for manipulating quantum states of any bosonic system in future quantum technologies, outline a possible application in quantum-enhanced sensing, and dispel a common misconception related to the nature of the increased phase sensitivity of multi-photon quantum states.

quant-ph↗