arXiv subjects

Pablo Vaveliuk

Publications and source records attributed to Pablo Vaveliuk.

6 recordsLinked to original sources

arXiv2021

Simple interferometric setup enabling sub-Fourier-scale ultra-short laser pulses

In this work, we have developed a method to generate ultra-short pulses below the Fourier limit, extending the concept previously worked in reference 1 for generating sub-diffractive Gaussian beams. Alternatively, we introduce new alternatives based on a temporally non-symmetrical interference to narrow ultrashort pulses allowing, sub-Fourier scales. The experimental setup scheme is simple and versatile being able to work with high-power laser sources and ultra-short pulses with a broad bandwidth at any central wavelength. The results presented, are promising and help to enlighten new routes and strategies in the design of coherent control systems. We glimpse they will become broadly useful in different fields from strong field domain to quantum information.

physics.optics↗

arXiv2021

Effective super-bandwidth in laser pulses

We present here a theoretical analysis of the interaction between an ideal two-level quantum system and a super-oscillatory pulse, like the one proposed and successfully synthesized in https://doi.org/10.1088/2040-8986/abfedf and arXiv:2106.09192. As a prominent feature, these pulses present a high efficiency of the central super-oscillatory region in relation to the unavoidable side-lobes. Besides, our study shows an increase of the effective bandwidth of the pulse, in the super-oscillatory region, and not only the appearance of a local frequency higher than its highest Fourier-frequency component, as in the usual description of the phenomenon of super-oscillations. Beyond introducing the concept of effective super-bandwidth, the presented results could be relevant for experimental applications and opening new perspectives for laser-matter interaction.

physics.optics↗

arXiv2021

Principal frequency of an ultrashort laser pulse

We introduce an alternative definition of the main frequency of an ultrashort laser pulse, the principal frequency $ω_P$. This parameter is complementary to the most accepted and widely used carrier frequency $ω_0$. Given the fact that these ultrashort pulses, also known as transients, have a temporal width comprising only few cycles of the carrier wave, corresponding to a spectral bandwidth $Δω$ covering several octaves, $ω_P$ describes, in a more precise way, the dynamics driven by these sources. We present examples where, for instance, $ω_P$ is able to correctly predict the high-order harmonic cutoff independently of the carrier envelope phase. This is confirmed by solving the time-dependent Schrödinger equation in reduced dimensions, supplemented with the time-analysis of the quantum spectra, where it is possible to observe how the sub-cycle electron dynamics is better described using $ω_P$. The concept of $ω_P$, however, can be applied to a large variety of scenarios, not only within the strong field physics domain.

physics.atom-ph↗

arXiv2015

Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus

Needle-like electromagnetic fields has various advantages for the applications in high-resolution imaging, Raman Spectroscopy, as well as long-distance optical transportation. The realization of such field often requires high numerical aperture (NA) objective lens and the transmission masks. We demonstrate an ultralong needle-like focus in the optical range produced with an ordinary lens. This is achieved by focusing a symmetric Airy beam (SAB) generated via binary spectral modulation with a digital micromirror device(DMD). Such amplitude modulation technique is able to shape traditional Airy beams, SABs, as well as the dynamic transition modes between the one-dimensional(1D) and two-dimensional (2D) symmetric Airy modes. The created 2D SAB was characterized through measurement of the propagating fields with one of the four main lobes blocked by an opaque mask. The 2D SAB was verified to exhibit self-healing property against propagation with the obstructed major lobe reconstructed after a certain distance. We further produced an elongated focal line by concentrating the SAB via lenses with different NA's, and achieved an ultralong longitudinal needle focus. The produced long needle focus will be applied in optical, chemical, and biological sciences.

physics.optics↗

arXiv2006

Alternative method for wave propagation analysis within bounded linear media: conceptual and practical implications

This paper uses an alternative approach to study the monochromatic plane wave propagation within dielectric and conductor linear media of plane-parallel-faces. This approach introduces the time-averaged Poynting vector modulus as field variable. The conceptual implications of this formalism are that the nonequivalence between the time-averaged Poynting vector and the squared-field amplitude modulus is naturally manifested as a consequence of interface effects. Also, two practical implications are considered: first, the exact transmittance is compared with that given by the Beer's Law, employed commonly in experiments. The departure among them can be significative for certain material parameter values. Second, when the exact reflectance is studied for negative permittivity slabs, it is show that the high reflectance can be diminished if a small amount of absorption is present.

physics.gen-ph↗

arXiv2005

Squared-field amplitude modulus and radiation intensity nonequivalence within nonlinear slabs

This paper presents a novel approach to wave propagation inside the Fabry-Perot framework. It states that the time-averaged Poynting vector modulus could be nonequivalent with the squared-field amplitude modulus. This fact permits the introduction of a new kind of nonlinear medium whose nonlinearity is proportional to the time-averaged Poynting vector modulus. Its transmittance is calculated and found to differ with that obtained for the Kerr medium, whose nonlinearity is proportional to the squared-field amplitude modulus. The latter emphasizes the nonequivalence of these magnitudes. A space-time symmetry analysis shows that the Poynting nonlinearity should be only possible in noncentrosymmetric materials.

physics.optics↗