Biomedical subjects

Miguel A Porras

Publications and source records attributed to Miguel A Porras.

3 recordsLinked to original sources

PubMed2003

Unified description of Bessel X waves with cone dispersion and tilted pulses.

We study Bessel X waves with cone dispersion propagating in free space and dispersive media. Their propagation features find simple explanation when viewed as cylindrically symmetric versions of the so-called tilted pulses. All previously reported cases of suppression of normal material group velocity dispersion by using angular dispersion in tilted pulses, pulsed Bessel beams, and Bessel X waves are compared and presented in a unified way. We show that stationary, spatiotemporal localized Bessel X-wave transmission is also possible in the anomalous dispersion regime.

Journal Article↗

PubMed2003

Paraxial envelope X waves.

Localized, stationary, X-type solutions of the paraxial wave equation are described. Unlike conventional X waves, these are luminal, envelope X waves sustained by a material medium because of the interplay of dispersion and diffraction.

Journal Article↗

PubMed2002

Diffraction effects in few-cycle optical pulses.

Basic concepts of three-dimensional wave packets are applied to the description of transverse effects on the propagation of ultrashort (femtosecond) pulses. The frequency-dependent nature of diffraction acts as a kind of dispersion that modifies the pulse front surface, its group velocity, the envelope form, and the carrier frequency. If the diffracted field in the monochromatic case is known, these changes can be straightforwardly quantified. Finding the propagated pulsed beam field reduces to a well-known and simpler problem of one-dimensional pulse propagation with group velocity dispersion. The method is applied to pulsed Gaussian beams and pulsed Bessel beams. Anomalous pulse front behavior, including superluminality in pulsed Gaussian beams is found. The carrier phase at any point of space is calculated.

Journal Article↗