Ottavia Jedrkiewicz

Colored conical emission by means of second-harmonic generation.

We predict that the combination of space and time modulational instabilities that occur by means of parametric wave mixing in quadratic media leads to colored conical emission. This phenomenon should be observed under conditions usually employed in second-harmonic experiments.

Complete retrieval of the field of ultrashort optical pulses using the angle-frequency spectrum

We propose an experimental technique that allows for a complete characterization of the amplitude and phase of optical pulses in space and time. By the combination of a spatially resolved spectral measurement in the near and far fields and a frequency-resolved optical gating measurement, the electric field of the pulse is obtained through a fast, error-reduction algorithm.

Finite-energy, accelerating Bessel pulses

We numerically investigate the possibility to generate freely accelerating or decelerating pulses. In particular it is shown that acceleration along the propagation direction z may be obtained by a purely spatial modulation of an input Gaussian pulse in the form of finite-energy Bessel pulses with a cone angle that varies along the radial coordinate.We discuss simple practical implementations of such accelerating Bessel beams.

Long spatio-temporally stationary filaments in air using short pulse UV laser Bessel beams

The formation of long stationary filaments resulting in uniform high density plasma strings in air using short pulse UV laser Bessel beams is shown. The length and the electron density of the plasma strings can be easily tuned by adjusting the conical Bessel wavefront angle. It is shown that in this regime the length of the plasma string can be extended over meter-long scales without any compromise in the string uniformity or any temporal evolution of the filamented laser pulse.

Impact of dimensionality on noise-seeded modulational instability

In second harmonic generation, the virtually infinite bandwidth of the spatio-temporal modulational instability leads to completely different scenarios for the wave-break when the input noise is monochromatic or when it carries a broad temporal spectrum.

Experimental Observation of the Ultra-narrow Temporal Entanglement of Twin Beams by Means of Frequency Up-conversion

We report here about the experimental observation of an ultra-narrow temporal correlation (6,7 fs FWHM) of twin beams produced by a type I BBO crystal, detected by means of the inverse process of sum-frequency generation.

Self-phase matching and X pulse formation in phase-mismatched second harmonic generation due to dimensionality transition

Since 1961, when Franken and his collaborators experimentally discovered second-harmonic generation (SHG) [1], the process of SHG has been widely investigated leading first to important contributions by many authors, who derived the now well-known theory described in nonlinear optics books. It was realized long time ago that the use of short light pulses for SHG gives rise to special effects, like the broadening of the generated light pulse due to the group velocity mismatch between the fundamental (FH) and second-harmonic (SH) pulses, predicted by Comly and coworkers [2] and observed for the first time by Shapiro [3]. Typically SHG is investigated or used at or near the phase-matching condition, in such a way to maximize the conversion efficiency. More recently the study of propagation phenomena in phase-mismatched second-harmonic processes has attracted considerable interest, in particular for the investigation of the effect on the generated pulse shape. However, typically mentioned studies were done in the case when the plane wave approximation is valid and SHG could be recognized as one-dimensional problem.

Generation and control of coherent conical pulses in seeded optical parametric amplification

We propose a new technique for high-energy conical pulse generation based on continuum seeded parametric amplification process in quadratic nonlinear media. We show that by using an appropriate broadband week seed we are able to lock the many spatiotemporal modes of the parametric radiation to obtain a single, coherent conical pulse.

Full Three Dimensional Intensity-and-Phase Retrieval of Arbitrarily Complex Ultrashort Laser Pulses

We propose a new experimental technique which allows for a complete characterization of amplitude and phase of the pulse in space and time whenever the pulse has a cylindrical geometry.