Jonathan Wheeler | Ecole polytechnique palaiseau (original) (raw)

Papers by Jonathan Wheeler

Journal of Physics B: Atomic, Molecular and Optical Physics, 2014

We demonstrate the generation of attosecond pulse trains (APTs) from high harmonics of Ti:Sapphir... more We demonstrate the generation of attosecond pulse trains (APTs) from high harmonics of Ti:Sapphire (800 nm) and OPA-produced MidIR (1300 -- 2200 nm) fundamental driving wavelengths in a new apparatus capable of performing typical pump/probe experiments between a laser pulse of the fundamental and its harmonic APT. Both beams are overlapped spatially and temporally in a magnetic bottle electron time-of-flight spectrometer allowing for measurements with high collection efficiency and energy resolution for the photoelectrons produced. We are further characterizing such features as spectral amplitude and phase of the attosecond harmonic bursts produced at longer fundamental wavelengths while also utilizing them in imaging and photo-ionization studies. Current progress and experimental results will be presented.

2008 Conference on Lasers and Electro-Optics, 2008

In our recent experiment we successfully generated forward-directed THz emission by 40-cm-long fi... more In our recent experiment we successfully generated forward-directed THz emission by 40-cm-long filamentation of an intense 0.8 mJ, 30-fs laser pulse in argon at 3 kHz repetition rate. We demonstrated that a specific filament pattern with two sequential focusing-...

Pushing the Frontiers of Atomic Physics - Proceedings of the XXI International Conference on Atomic Physics, 2009

The genesis of light pulses with attosecond (10-18 seconds) durations signifies a new frontier in... more The genesis of light pulses with attosecond (10-18 seconds) durations signifies a new frontier in time-resolved physics. The scientific importance is obvious: the time-scale necessary for probing the motion of an electron(s) in the ground state is attoseconds (atomic unit of time = 24 as). The availability of attosecond pulses would allow, for the first time, the study of the

2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007

... JWD4 JWE4.pdf © 2007 OSA/CLEO 2007 Page 2. 900 750 600 450 300 150 0 Shot number ... Soc. Am.... more ... JWD4 JWE4.pdf © 2007 OSA/CLEO 2007 Page 2. 900 750 600 450 300 150 0 Shot number ... Soc. Am. B 19, 330 (2000) 3. BJ Pearson, JL White, TC Weinacht, PH Bucksbaum, Phys. Rev. A 6 3 , 063412 (2002) JWD4 JWE4.pdf © 2007 OSA/CLEO 2007

ABSTRACT Spatio-temporal coupling (STC) within a laser pulse is normally a negative feature to be... more ABSTRACT Spatio-temporal coupling (STC) within a laser pulse is normally a negative feature to be avoided as it leads to non-uniform pulse characteristics and reduced intensity at focus. In this study, STC is purposefully introduced into the laser pulse leading to wavefront rotation at the focus. When such a modified focus is applied to plasma mirror harmonic generation, each harmonic pulse produced from cycle to cycle has a shifted propagation direction. Dependant on the degree of wavefront rotation introduced, this can lead from tilted harmonic spectra due to small displacements of the overlapping beams to fully isolated, individual pulses arising from each cycle of the driving laser pulse, the so-called Attosecond Lighthouse effect. This work discusses the recently measured results of spatially-separated, single harmonic beams from a solid target source obtained with 1kHz, CEP-locked, 800nm laser pulses of both 25 and 5 fs duration.

ABSTRACT The genesis of light pulses with attosecond (10-18 seconds) durations signifies a new fr... more ABSTRACT The genesis of light pulses with attosecond (10-18 seconds) durations signifies a new frontier in time-resolved physics. The scientific importance is obvious: the time-scale necessary for probing the motion of an electron(s) in the ground state is attoseconds (atomic unit of time = 24 as). The availability of attosecond pulses would allow, for the first time, the study of the time-dependent dynamics of correlated electron systems by freezing the motion, in essence exploring the structure with ultra-fast snapshots, then following the subsequent evolution using pump-probe techniques. This paper examines the fundamental principles of attosecond formation by Fourier synthesis of a high harmonic comb and phase measurements using two-color techniques. Quantum control of the spectral phase, critical to attosecond formation, has its origin in the fundamental response of an atom to an intense electromagnetic field. We will interpret the laser-atom interaction using a semi-classical trajectory model.

2009 Conference on Lasers & Electro Optics & The Pacific Rim Conference on Lasers and Electro-Optics, 2009

... "Scaling strong-field interactions towards ithe classical limit" Nat. Phys.4, 386 (... more ... "Scaling strong-field interactions towards ithe classical limit" Nat. Phys.4, 386 (2008) [2] G. Doumy, J. Wheeler, C. Roedig, R. Chirla, P. Agostini, and LF DiMauro Attosecond Synchronization of High-Order Harmonics from Midinfrared Drivers Phys. Rev. ... CLEO Pacific Rim 2009

Commercial and Biomedical Applications of Ultrafast Lasers VII, 2007

This document reports recent theoretical and experimental investigations of strong field ionizati... more This document reports recent theoretical and experimental investigations of strong field ionization and high harmonic generation from mid-infrared lasers at 2 and 4 microns. Numerical solution of the time-dependent Schrodinger equation as well as Strong Field approximation calculations are reported. Photoelectron and high harmonic spectra are discussed. Preliminary experimental results are compared to the theoretical predictions.

Physical Review Letters, 2009

The group delay dispersion, also known as the attochirp, of high-order harmonics generated in gas... more The group delay dispersion, also known as the attochirp, of high-order harmonics generated in gases has been identified as the main intrinsic limitation to the duration of Fourier-synthesized attosecond pulses. Theory implies that the attochirp, which is inversely proportional to the laser wavelength, can be decreased at longer wavelength. Here we report the first measurement of the wavelength dependence of the attochirp using an all-optical, in situ method [N. Dudovich, Nature Phys. 2, 781 (2006)10.1038/nphys434]. We show that a 2 microm driving wavelength reduces the attochirp with respect to 0.8 microm at comparable intensities.

Physical Review Letters, 2014

High harmonic generation (HHG) is used to measure the spectral phase of the recombination dipole ... more High harmonic generation (HHG) is used to measure the spectral phase of the recombination dipole matrix element (RDM) in argon over a broad frequency range that includes the 3p Cooper minimum (CM). The measured RDM phase agrees well with predictions based on the scattering phases and amplitudes of the interfering s- and d-channel contributions to the complementary photoionization process. The reconstructed attosecond bursts that underlie the HHG process show that the derivative of the RDM spectral phase, the group delay, does not have a straightforward interpretation as an emission time, in contrast to the usual attochirp group delay. Instead, the rapid RDM phase variation caused by the CM reshapes the attosecond bursts.

Optics Letters, 2007

We report the compression of intense, carrier-envelope phase stable mid-IR pulses down to few-cyc... more We report the compression of intense, carrier-envelope phase stable mid-IR pulses down to few-cycle duration using an optical filament. A filament in xenon gas is formed by using self-phase stabilized 330 J 55 fs pulses at 2 m produced via difference-frequency generation in a Ti:sapphire-pumped optical parametric amplifier. The ultrabroadband 2 m carrier-wavelength output is self-compressed below 3 optical cycles and has a 270 J pulse energy. The self-locked phase offset of the 2 m difference-frequency field is preserved after filamentation. This is to our knowledge the first experimental realization of pulse compression in optical filaments at mid-IR wavelengths ͑Ͼ0.8 m͒.

Nature Physics, 2008

In 1964 Keldysh 1 helped lay the foundations of strong-field physics by introducing a theoretical... more In 1964 Keldysh 1 helped lay the foundations of strong-field physics by introducing a theoretical framework that characterized atomic ionization as a process that evolves with the intensity and wavelength of the fundamental field. Within this context, experiments 2 have examined the intensity-dependent ionization but, except for a few cases, technological limitations have confined the majority to wavelengths below 1 µm. The development of intense, ultrafast laser sources in the midinfrared (1 µm < l < 5 µm) region enables exploration of the wavelength scaling of the Keldysh picture while enabling new opportunities in strong-field physics, control of electronic motion and attosecond science. Here we report a systematic experimental investigation of the wavelength scaling in this region by concurrently analysing the production of energetic electrons and photons emitted by argon atoms interacting with few-cycle, mid-infrared fields. The results support the implicit predictions contained in Keldysh's work, and pave the way to the realization of brighter and shorter attosecond pulsed light sources using longer-wavelength driving fields.

Journal of Modern Optics, 2007

The generation of short, intense, mid-infrared laser pulses allows for the exploration of atom-la... more The generation of short, intense, mid-infrared laser pulses allows for the exploration of atom-laser interactions deep in the tunneling regime as well as providing the ability to explore scaled interactions. In this paper we present recent experimental and theoretical results for this largely unexplored parameter space.

The generation of light pulses with attosecond (10 −18 seconds) duration is studied using laser d... more The generation of light pulses with attosecond (10 −18 seconds) duration is studied using laser drivers operating in the mid-infrared region. This paper first examines the fundamental principles of attosecond formation by Fourier synthesis of a high harmonic comb. Experimental demonstration of the extension of the harmonic cutoff is shown using a 2 micron driver. Then, the crucial spectral phase properties, responsible for the pulse structure on the attosecond time scale, are measured with an all-optical technique using a mix of the fundamental pulse with its second harmonic. The expected 1/λ scaling is verified, which demonstrates a practical way towards pulses approaching the atomic unit of time (24 as).