An electron generated by x-ray photoionization can be deflected a strong laser field. Its energy and angular distribution depends on the phase of field at time ionization. This dependence used to measure duration chirp single sub100-attosecond pulses.

We describe a method for the complete temporal characterization of attosecond extreme ultraviolet (xuv) fields. An electron wave packet is generated in continuum by photoionizing atoms with field, and low-frequency dressing laser pulse used as phase gate frequency-resolved-optical-gating-like measurements on this packet. This valid xuv fields an arbitrary structure, e.g., trains nonidentical pulses. It establishes direct connection between main techniques demonstrated experimentally so far,...

We present a new mechanism for high-order harmonic generation by reflection of laser beam from an overdense plasma, efficient even at moderate intensities (down to $I{\ensuremath{\lambda}}^{2}\ensuremath{\approx}4\ifmmode\times\else\texttimes\fi{}{10}^{15}\text{ }\text{ }\mathrm{W}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }\ensuremath{\mu}{\mathrm{m}}^{2}$). In this mechanism, transient phase matching between the electromagnetic field and plasma oscillations within density gradient leads...

Under the effect of even simple optical components, spatial properties femtosecond laser beams can vary over duration light pulse. We show how using such spatiotemporally coupled fields in high harmonic generation experiments (e.g., gases or dense plasmas) enables production attosecond lighthouses, i.e., sources emitting a collection angularly well-separated beams, each consisting an isolated This general opens way to new sources, particularly suitable for pump-probe experiments, and...

Improving the temporal contrast of ultrashort and ultraintense laser pulses is a major technical issue for high-field experiments. This can be achieved using so-called "plasma mirror." We present detailed experimental theoretical study plasma mirror that allows us to quantitatively assess performances this system. Our results include time-resolved measurements reflectivity, phase distortions it induces on reflected beam. Using an antireflection coated plate as target, improvement ratio by...

When an intense femtosecond laser pulse hits optically polished surface, it generates a dense plasma that itself acts as mirror, known the mirror. As this mirror reflects high-intensity field, its nonlinear temporal response can lead to periodic distortion of reflected wave, associated with train attosecond light pulses, and, in frequency domain, generation high-order harmonics laser. This tutorial presents detailed theoretical and numerical analysis two dominant harmonic mechanisms...

We present and characterize a very efficient optical device that employs the plasma mirror technique to increase contrast of high-power laser systems. Contrast improvements higher than 10(4) with 50% transmission are shown be routinely achieved on typical 10 TW system when pulse is reflected two consecutive mirrors. Used at end system, this double preserves spatial profile initial beam, unaffected by shot-to-shot fluctuations, suitable for most high peak power use generation high-order...

Because of their broad spectral width, ultrashort lasers provide unique possibilities to shape light beams and control properties, in particular through the use spatio-temporal couplings.In this context, we present a theoretical investigation linear propagation laser that combine temporal chirp standard aberration known as longitudinal chromatism.When such are focused vacuum, or medium, interplay these two effects can be exploited set velocity resulting intensity peak arbitrary values within...

High-order harmonics and attosecond pulses of light can be generated when ultraintense, ultrashort laser reflect off a solid-density plasma with sharp vacuum interface, i.e., mirror. We demonstrate experimentally the key influence steepness plasma-vacuum interface on interaction, by measuring spectral spatial properties mirror whose initial density gradient scale length $L$ is continuously varied. Time-resolved interferometry used to separately measure this length.

The advent of ultrahigh-power femtosecond lasers creates a need for an entirely new class optical components based on plasmas. most promising these are known as plasma mirrors, formed when intense laser ionizes solid surface. These mirrors specularly reflect the main part pulse and can be used active elements to manipulate its temporal spatial properties. Unfortunately, considerable pressures exerted by deform mirror surface, unfavourably affecting reflected beam complicating, or even...

Laser beams carrying orbital angular momentum (OAM) have found major applications in a variety of scientific fields, and their potential for ultrahigh-intensity laser-matter interactions has since recently been considered theoretically. We present an experiment where such interact with plasma mirrors up to laser intensities that the motion electrons field is relativistic. By measuring spatial intensity phase profiles high-order harmonics generated reflected beam, we obtain evidence helical...

We introduce a new class of spatio-temporally coupled ultrashort laser beams, which are obtained by superimposing Laguerre-Gauss beams whose azimuthal mode index is correlated to their frequency. These characterized helical structures for phase and intensity profiles, both encode the orbital angular momentum carried light. They can easily be engineered in optical range, naturally produced at shorter wavelengths when attosecond pulses generated intense femtosecond beams. spatio-temporal...

The temporal characterization of ultrafast laser pulses has become a cornerstone capability optics laboratories and is routine both for optimizing pulse duration designing custom fields. Beyond pure characterization, spatio-temporal provides more complete measurement the spatially-varying properties pulse. These so-called couplings (STCs) are generally nonseparable chromatic aberrations that can be induced by very common optical elements -- example diffraction gratings thick lenses or prisms...

We propose a twisted plasma accelerator capable of generating relativistic electron vortex beams with helical current profiles. The angular momentum these bunches is quantized, dominates their transverse motion, and results in spiraling particle trajectories around the wakefield. focus on laser wakefield acceleration scenario, driven by beam spatiotemporal intensity profile, also known as light spring. find that springs can rotate they excite wakefield, providing new mechanism to control...

The interaction of intense laser beams with plasmas created on solid targets involves a rich non-linear physics. Because such dense are reflective for light, the coupling incident beam occurs within thin layer at interface between plasma and vacuum. One main paradigms used to understand this coupling, known as Brunel mechanism, is expected be valid only very steep surfaces. Despite innumerable studies, its validity range remains uncertain, physics involved smoother plasma-vacuum interfaces...

We present the first femtosecond time-resolved study of evolution laser-excited carrier density with laser intensity, in various dielectrics practical interest (SiO2, Al2O3, MgO) both above and below breakdown threshold. These measurements demonstrate that high electronic excitation responsible for optical these solids is produced by multiphoton absorption valence electrons, pulses shorter than a few ps. No sign avalanche has been observed such short pulses.

Building on the concepts developed for femtosecond metrology, this paper proposes a unified perspective of different techniques temporal characterization attosecond XUV fields. These rely conversion field to be characterized into continuum electron wavepacket replica, through single-photon photoionization an atom. A dressing laser is then used as ultrafast phase modulator wavepacket, instance allowing one shear or streak it in energy. We present ways using time-nonstationry filter with...

This paper provides an overview of ultrafast wavefront rotation femtosecond laser pulses and its various applications in highly nonlinear optics, focusing on processes that lead to the generation high-order harmonics attosecond pulses. In this context, can be exploited different ways, obtain new light sources for time-resolved studies, called 'attosecond lighthouses', perform measurements optical processes, using 'photonic streaking', or track changes carrier–envelope relative phase The...

A general approach for optically controlled spatial structuring of overdense plasmas generated at the surface initially plain solid targets is presented. We demonstrate it experimentally by creating sinusoidal plasma gratings adjustable periodicity and depth, study interaction these transient structures with an ultraintense laser pulse to establish their usability relativistically high intensities. then show how can be used as a "spatial ruler" determine source size high-order harmonic beams...