Dark matter is a key ingredient to physical cosmology, and one of the mysteries of modern science. Among a variety of possible candidates which have been explored in recent decades (such as WIMPs and WISPs), the axions are the most promising constituents of dark matter. These hypothetical particles have been proposed to solve fundamental problems of charge- parity (CP) invariance and their discovery could therefore solve two important problems in cosmology and in particle physics. The axions, and axion-like particles, have been actively searched without success since the 80’s of the last century, using both laboratory experiments and astrophysical observations. In recent years, it became clear that the axions, if they exist, could be actively produced by intense laser pulses in magnetised and unmagnetised vacuum, and that the axion field could become unstable under the action of intense laser beams. Alternatively, the signature of axions could possibly be found in the dispersion relation of electrostatic waves in strongly magnetised plasmas, due to the formation of the axion-plasmon mode. This new mode could be excited by intense laser pulses in a plasma. In the present work, we consider different configurations leading to the excitation of axions by intense laser pulses, and consider propagation both in vacuum and in plasmas. A discussion of possible experimental arrangements, using the available laser technology is included.
The problem of electromagnetic wave propagation in time varying media is very old, but in recent years it has been revisited at a more fundamental level leading to the introduction of several new concepts, such as Time Refraction. These concepts explore the symmetries between space and time and can be transposed to different fields by establishing powerful analogies between effects in Electrodynamics, Optics and problems in Quantum Cosmology and in what is sometimes called Analogue Gravity. We examine the alteration of the ordinary (spatial) Fresnel laws of refraction at the interface between two media when the optical properties of one of the media varies in time.
We present an alternative description of nonlinear cross-phase modulation based on the kinetic equation for photons. The most relevant feature of this new approach is that phase itself is completely ignored. Formal exact solutions and approximate analytical solutions are discussed. Experimental measurements of cross-phase modulation of two-color ultrashort laser pulses propagating in a highly nonlinear photonic crystal fiber reveal a good agreement with the analytical results.
Photon Landau damping of electron plasma waves with relativistic phase velocity has
been rst considered in 1997, in the frame of geometric optics [1]. Here we consider more
recent results based on a kinetic model where photon recoil is taken into account [2]. By
photon recoil we mean the change of a nite amount of momentum by photons, due to
the emission or the absorption of electron plasma waves. This gives a surprising quantum
avor to a purely classical description. Our approach is based on an exact form of the
wave kinetic equation. Kinetic and uid regimes of photon beam instabilities, and their
relevance to particle acceleration and new radiation sources are discussed. Quasi-lnear
results leading to a photon Boltzmann equation are also discussed. Diusion in the photon
momentum space are shown to be a consequence of photon-plasmon collisions, taken in the
geometric optics limit. A brief discussion of photon trapping by the plasma wave potential
is also included. Our theoretical discussion will be illustrated with the description of
recent experimental results using intense laser plasma interactions, as well as with a new
experimental proposal.
The Laboratory for Intense Lasers (L2I) facility is equipped with a multi-Terawatt Ti:sapphire-Nd:glass chirped pulse amplification laser system delivering 2.8 TW pulses at 1053 nm. Here we present the laser configuration and characterize its current performance, and describe the diagnostics and methods used for this characterization.
Angular dispersion of the signal beam inside the nonlinear media is taken into account to improve the non-collinear phase-matching range. Simulations ran for BBO, LBO and KDP crystals predict that bandwitdth increase is possible for most of the application spectral range and that is can surpass one order of magnitude in some particular configurations.
KEYWORDS: Laser systems engineering, Pulsed laser operation, Interferometry, Oscillators, Spectroscopy, Calibration, Diffraction gratings, Control systems, High power lasers, Crystals
We present a device for spectral phase pulse diagnosis assembled to optimize and control pulse compression in our chirped pulse amplification (CPA) laser system at Laboratorio de Lasers Intensos (L2I). The device uses the spectral interferometry for direct electric-field reconstruction (SPIDER) technique and, together with a pulse spectral intensity acquisition, allows the complete temporal and spectral characterization of the pulses. Using the device and our own real-time software we successfully optimized the compression and characterized the final terawatt pulses. We also describe here a new simple interferometric method to directly measure a calibration constant of the SPIDER setup and control the temporal overlapping of the two replicas and chirped pulse in SPIDER. A study is presented that allows the measure of chirps in pulses far above the normally accepted dispersion limit of a SPIDER diagnosis.
We report on the efficient spectral control of ultrashort sub-nanojoule violet laser pulses by means of cross-phase modulation (XPM) with a pump pulse in a highly nonlinear photonic crystal fiber (PCF). Spectra of the output pulses were recorded as a function of pump-probe delay for different pump central wavelengths. For fiber lengths that are much longer than the pulse walk-off distance, we consistently observe simultaneous downshifted and upshifted bands in the output pulses, associated with the frequency shift induced by both the leading and trailing edges of the pump as it sweeps over the probe pulses. These features can only be observed with pump pulses propagating in the anomalous dispersion region of the PCF, where pump pulse compression occurs and provides the necessary pump asymmetry.
The concepts of time refraction was introduced in recent years, as the temporal analogue of the usual (space) refraction, for waves propagating in non-stationary optical media. We discuss possible experimental configurations for time refraction of low intensity and short laser pulses propagating in optical fibers, and their eventual use in photonics. We generalize our previous work to the case of guided propagation. The expected frequency shifts, amplitudes and shapes of the secondary pulses resulting from time refraction are calculated.
We report on simulations of atomic cluster explosions upon interaction with high-intensity femtosecond laser pulses. By using a 2D and 3D fully relativistic PIC code we investigate the dynamics of hydrogen and argon cluster explosions providing information about the time-resolved ion energy spectra, for different laser intensities. Multi-cluster systems are also studied and the influence of cluster distribution in ionic energy spectra is shown. Results indicate that MeV ions are produced through Coulomb explosion of the atomic clusters and the possibility of capturing most of these ions with a specially designed magnetic focusing system is discussed.
New results from the interaction of ultra short laser pulses with ionization fronts are presented. The frequency up- shifts, due to photon acceleration, were obtained in a co- and counter propagation scheme. The different levels of frequency up-shift observed give us not only the overall plasma density but also information about the fine structure of the ionization font. The correlation between the interaction lengths for co- and counter-propagation, with the longitudinal and transverse dimensions of the ionization front is also discussed. Those result clearly show the capability of using photon acceleration phenomena to fully characterize a relativistic ionization front.
We propose to use nondegenerate cascaded four-wave mixing processes for efficient high order harmonic generation in plasmas and dielectrics. A simple model is used to estimate the temporal duration and maximum order of the generated harmonics for both a typical laser-produced plasma and glass slide. In the plasma case, we expect considerable pulse compression, with the production of sub-femtosecond pulses starting from the 8th harmonic.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.