Publications by Adam Wyatt


Attosecond sampling of arbitrary optical waveforms

2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013 (2013)

AS Wyatt, T Witting, A Schiavi, D Fabris, JP Marangos, JWG Tisch, IA Walmsley

Arbitrary waveform synthesis [1] offers the possibility to study and control electronic and nuclear processes with attosecond temporal resolution [2], and to enable 'sub-cycle' pulses and optimize high harmonic generation (HHG) [3, 4]. Appropriate metrology is critical to ensure the correct waveform is generated at the location of the experiment. Solutions to this measurement problem must deliver (a) adequate bandwidth; (b) sufficient efficiency; (c) sensitivity to phase across well-separated spectral components; (d) sensitivity to carrier-envelope phase (CEP); (e) reliable calibration procedures that can account for propagation between the measurement instrument and the experiment itself. Here we describe an experimental demonstration of the first all-optical method to characterize in-situ the real electric field of an arbitrary optical waveform based on HHG. © 2013 IEEE.


Attosecond Sampling of Arbitrary Optical Waveforms

2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE AND INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE (CLEO EUROPE/IQEC) (2013)

AS Wyatt, T Witting, A Schiavi, D Fabris, JP Marangos, JWG Tisch, IA Walmsley, IEEE


Generalized multishearing interferometry for the complete multidimensional characterization of optical beams and ultrashort pulses

2012 Conference on Lasers and Electro-Optics, CLEO 2012 (2012)

AS Wyatt, J Biegert, IA Walmsley

We demonstrate increased accuracy and precision in the reconstruction of the multidimensional phase of electromagnetic fields based on multiple spectral shearing interferometry measurements made with shears of an arbitrary magnitude. © 2012 OSA.


Vectorial phase retrieval for linear characterization of attosecond pulses

High Intensity Lasers and High Field Phenomena, HILAS 2012 (2012)

O Raz, O Schwartz, B Nadler, D Oron, N Dudovich, D Austin, AS Wyatt, A Schiavi, IA Walmsley, O Smirnova

We propose a new linear and all-optical method for attosecond pulses characteri-zation. Our scheme is based only on spectral and polarization measurements. We demonstrate this method numerically on attosecond pulses generated from aligned CO molecules. © 2011 Optical Society of America.


Lateral shearing interferometry of high-harmonic wavefronts

Opt. Lett. OSA 36 (2011) 10

DR Austin, T Witting, CA Arrell, F Frank, AS Wyatt, JP Marangos, JWG Tisch, IA Walmsley

We present a technique for frequency-resolved wavefront characterization of high harmonics based on lateral shearing interferometry. Tilted replicas of the driving laser pulse are produced by a Mach–Zehnder interferometer, producing separate focii in the target. The interference of the resulting harmonics on a flat-field extreme ultraviolet spectrometer yields the spatial phase derivative. A comprehensive set of spatial profiles, resolved by harmonic order, validate the technique and reveal the interplay of single-atom and macroscopic effects.


Vectorial phase retrieval for linear characterization of attosecond pulses

Physical Review Letters 107 (2011)

O Raz, O Schwartz, D Austin, AS Wyatt, A Schiavi, O Smirnova, B Nadler, IA Walmsley, D Oron, N Dudovich

The waveforms of attosecond pulses produced by high-harmonic generation carry information on the electronic structure and dynamics in atomic and molecular systems. Current methods for the temporal characterization of such pulses have limited sensitivity and impose significant experimental complexity. We propose a new linear and all-optical method inspired by widely used multidimensional phase retrieval algorithms. Our new scheme is based on the spectral measurement of two attosecond sources and their interference. As an example, we focus on the case of spectral polarization measurements of attosecond pulses, relying on their most fundamental property-being well confined in time. We demonstrate this method numerically by reconstructing the temporal profiles of attosecond pulses generated from aligned CO2 molecules. © 2011 American Physical Society.


Accuracy measurements and improvement for complete characterization of optical pulses from nonlinear processes via multiple spectral-shearing interferometry

OPTICS EXPRESS 19 (2011) 25355-25366

AS Wyatt, A Gruen, PK Bates, O Chalus, J Biegert, IA Walmsley


Vectorial phase retrieval for linear characterization of attosecond pulses

Optics InfoBase Conference Papers (2011)

O Raz, O Schwartz, D Austin, AS Wyatt, A Schiavi, O Smirnova, B Nadler, IA Walmsley, D Oron, N Dudovich

We propose a new linear and all-optical method for attosecond pulses characteri-zation. Our scheme is based only on spectral and polarization measurements. We demonstrate this method numerically on attosecond pulses generated from aligned CO2 molecules. © 2011 Optical Society of America.


Measuring sub-Planck structural analogues in chronocyclic phase space

Optics Communications Elsevier 283 (2010) 5

DR Austin, T Witting, AS Wyatt, IA Walmsley

Phase space quasi-probability distributions of certain quantum states reveal structure on a scale that is small compared to the Planck area. Using an analog between the wavefunction of a single photon and the electric field of a classical ultrashort optical pulse we show that spectral shearing interferometry enables measurement of such structure directly, thereby extending an idea of Krzysztof Wódkiewicz and others. In particular, we use multiple-shear spectral interferometry to fully characterize a pulse consisting of two sub-pulses which are temporally and spectrally disjoint, without a relative-phase ambiguity. This enables us to compute the Wigner distribution of the pulse. This spectrographic representation of the pulse field features fringes that are tilted with respect to both the time- and frequency axes, showing that in general the shortest sub-Planck distances may not be in the directions of the canonical (and easily experimentally accessible) directions. Further, independent of this orientation, evidence of the sub-Planck scale of the structure may be extracted directly from the measured signal.


Ionization effects on spectral signatures of quantum-path interference in high-harmonic generation

Opt. Express OSA 17 (2009) 7

M Holler, A Zaïr, F Schapper, T Auguste, E Cormier, A Wyatt, A Monmayrant, IA Walmsley, L Gallmann, P Salières, U Keller

The interference between the emission originating from the short and long electron quantum paths is intrinsic to the high harmonic generation process. We investigate the universal properties of these quantum-path interferences in various generation media and discuss how ionization effects influence the observed interference structures. Our comparison of quantum-path interferences observed in xenon, argon, and neon demonstrates that our experimental tools are generally applicable and should also allow investigating more complex systems such as molecules or clusters.


Theoretical and experimental analysis of quantum path interferences in high-order harmonic generation

Phys. Rev. A American Physical Society 80 (2009) 033817-033817

T Auguste, P Salières, AS Wyatt, A Monmayrant, IA Walmsley, E Cormier, A Zaïr, M Holler, A Guandalini, F Schapper, J Biegert, L Gallmann, U Keller

We present theoretical and experimental studies on quantum path interferences in high-order harmonic generation. Simulations of the single-atom response allow us to calculate the different quantum paths contributions; their relative phases and the resulting interferences can be finely controlled through the laser intensity that provides an efficient means for controlling the electron trajectories with an accuracy on the ten attoseconds time scale. Simulations of the macroscopic response demonstrate the need of spatial and spectral filtering of the harmonic beam in order to observe the interferences between the two shortest quantum paths. Our numerical results are in very good agreement with experimental data. These investigations represent a step toward the full characterization and control of the atomic harmonic dipole.


Quantum path interferences in high-harmonic generation: Ionization effects and spatial structure

2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009 (2009)

L Gallmann, M Holler, A Zaïr, F Schapper, T Auguste, E Cormier, A Wyatt, A Monmayrant, IA Walmsley, P Salières, U Keller

We investigate the influence of microscopic and macroscopic ionization effects on the intensity-dependent quantum-path interferences in high-harmonic generation. The resulting interference structures were analyzed in different gases and in spatially resolved harmonic spectra. © 2009 Optical Society of America.


Quantum Path Interferences in High-Harmonic Generation: Ionization Effects and Spatial Structure

Conference on Lasers and Electro-Optics/International Quantum Electronics Conference Optical Society of America (2009) JThH6-

Lukas Gallmann, Mirko Holler, Amelle Za�r, Florian Schapper, Thierry Auguste, Eric Cormier, Adam Wyatt, Antoine Monmayrant, Ian A. Walmsley, Pascal Sali�res, Ursula Keller


Direct observation of quantum-path interferences in high order harmonic generation

The European Physical Journal - Special Topics Springer Berlin / Heidelberg 175 (2009) 191-194-191-194

E Cormier, A Zaïr, M Holler, F Schapper, U Keller, A Wyatt, A Monmayrant, I Walmsley, T Auguste, P Salières

Intensity dependent high harmonic generation was investigated when both short and long trajectories contribute to the emission. We have directly observed for the first time clear indication of quantum-path interference through harmonic spectrum modulations.


Analysis of space-time coupling in SEA-SPIDER measurements

Lasers and Electro-Optics 2009 and the European Quantum Electronics Conference. CLEO Europe - EQEC 2009. European Conference on (2009) 1-1

AS Wyatt, IA Walmsley

Pulse characterisation methods based on non-collinear frequency mixing (NCFM) can introduce additional space-time coupling (STC) in the measurement. Thus it is necessary to re-examine the NCFM process in order to be able to measure STC accurately with these devices. SEA-SPIDER is one characterisation method that in principle can measure the temporal electric field of a pulse as a function of a single spatial dimension, thus measuring STC (but not the spatial phase). This method has been modelled specifically and found it is necessary to account for this additional ’geometric’ STC for few-cycle pulses. SEA-SPIDER has already been demonstrated as an excellent candidate for measuring extremely large bandwidth pulses. In addition, it has been shown that it is possible to measure the STC of a pulse in one spatial dimension. However, the non-collinear sum-frequency generation used in the device introduces a small amount of additional STC coupling which can easily be corrected for. This analysis will prove invaluable as it allows one to obtain more complete and accurate information about their pulses. The ideas and analysis presented here can also be applied to other characterisation methods that claim to be able to measure STC.


Study of quantum-path interferences in the high harmonic generation process

Springer Berlin Heidelberg 92 (2009) 27-29-27-29

A Zaïr, M Holler, F Schapper, L Gallmann, A Wyatt, A Monmayrant, T Auguste, J Pascal-Caumes, I Walmsley, E Cormier, P Salièeres, U Keller

High Harmonic generation can be used as a probe of the emitting medium with attosecond and Angström resolutions. We show that polarization-resolved pump-probe spectroscopy with high harmonics improves the detection sensitivity of rotationally excited molecules.


Quantum Path Interferences in High-Harmonic Generation: Ionization Effects and Spatial Structure

2009 CONFERENCE ON LASERS AND ELECTRO-OPTICS AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2009), VOLS 1-5 (2009) 2713-+

L Gallmann, M Holler, A Zair, F Schapper, T Auguste, E Cormier, A Wyatt, A Monmayrant, IA Walmsley, P Salieres, U Keller, IEEE


Increasing the consistency and accuracy of spectral shearing interferometry via multiple shearing

2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009 (2009)

AS Wyatt, DR Austin, T Witting, IA Walmsley, A Grün, PK Bates, O Chalus, J Biegert

We demonstrate improved accuracy and consistency for spectral-shearing interferometry using multiple shears. Using a new algorithm, different spectral shears are combined to perform accurate spectral phase measurements of complicated pulses from a hollow-core fiber system. © 2008 Optical Society of America.


Quantum Path Interferences in High-Order Harmonic Generation

Physical Review Letters APS 100 (2008) 14

A Zair, M Holler, A Guandalini, F Schapper, J Biegert, L Gallmann, U Keller, AS Wyatt, A Monmayrant, IA Walmsley, E Cormier, T Auguste, JP Caumes, P Salieres

We have investigated the intensity dependence of high-order harmonic generation in argon when the two shortest quantum paths contribute to the harmonic emission. For the first time to our knowledge, experimental conditions were found to clearly observe interference between these two quantum paths that are in excellent agreement with theoretical predictions. This result is a first step towards the direct experimental characterization of the full single-atom dipole moment and demonstrates an unprecedented accuracy of quantum path control on an attosecond time scale.


Two-quantum-path interferences in high order harmonic generation

Optics InfoBase Conference Papers (2007)

A Zaïr, M Holler, A Guandalini, F Schapper, J Biegert, U Keller, P Salières, T Auguste, E Cormier, A Wyatt, A Monmayrant, I Walmsley

We have investigated intensity dependent high-harmonic generation, when short and long trajectories are both visible in the generated signal. We have measured a plateau-harmonic spectral broadening and yield modulations consistent with quantum-paths interferences calculations. © 2007 Optical Society of America.

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