Publications by authors named "Philippe Lassonde"

13 Publications

  • Page 1 of 1

Single-shot phase-matching free ultrashort pulse characterization based on transient absorption in solids.

Opt Express 2020 Nov;28(24):35807-35815

The frequency-resolved optical switching (FROSt) method developed for ultrashort pulse characterization is implemented for single-shot measurements. In this basic demonstration, the delay axis of the spectrogram is spatially encoded by the pump beam having a small incident angle with the photoexcited material. We present the calibration procedure for spectrograms acquired in single-shot and the temporal characterization of 44 fs pulses with central wavelength at 800 nm both in scanning and single-shot FROSt configurations. The retrieved pulses are compared by means of the root-mean-square field error. Finally, the pulses are propagated through a known dispersive material to measure the added group-delay dispersion.
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http://dx.doi.org/10.1364/OE.409342DOI Listing
November 2020

Capturing roaming molecular fragments in real time.

Science 2020 11;370(6520):1072-1077

Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, Varennes, Quebec J3X 1S2, Canada.

Since the discovery of roaming as an alternative molecular dissociation pathway in formaldehyde (HCO), it has been indirectly observed in numerous molecules. The phenomenon describes a frustrated dissociation with fragments roaming at relatively large interatomic distances rather than following conventional transition-state dissociation; incipient radicals from the parent molecule self-react to form molecular products. Roaming has been identified spectroscopically through static product channel-resolved measurements, but not in real-time observations of the roaming fragment itself. Using time-resolved Coulomb explosion imaging (CEI), we directly imaged individual "roamers" on ultrafast time scales in the prototypical formaldehyde dissociation reaction. Using high-level first-principles simulations of all critical experimental steps, distinctive roaming signatures were identified. These were rendered observable by extracting rare stochastic events out of an overwhelming background using the highly sensitive CEI method.
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http://dx.doi.org/10.1126/science.abc2960DOI Listing
November 2020

Information transfer via temporal convolution in nonlinear optics.

Sci Rep 2020 Sep 11;10(1):14969. Epub 2020 Sep 11.

INRS-EMT, 1650 Blvd Lionel-Boulet, Varennes, QC, J3X1S2, Canada.

Nonlinear parametric processes involving ultrashort pulses are typically carried out in time domain, which mathematically corresponds to a convolution of their frequency spectra. In contrast, this spectral convolution changes into a multiplication operation when performing the nonlinear interaction in frequency domain. Here, we extend the scope of frequency-domain nonlinear optics by demonstrating its ability to perform a temporal convolution. Through this approach, nonlinear optical operations that are inaccessible in time domain can be realised: specific optical information can be coherently advanced by picoseconds within a pulse sequence-a newly generated second harmonic pulse carries the amplitude and phase information of two input pulses. This central pulse is isolated when using an input field consisting of two cross-polarized input pulses in combination with type-II second harmonic generation. The effects of nonlinear temporal convolution can be viewed from the aspect of signal processing and pulse shaping, where the nonlinear interaction in the parametric crystal plays the role of a dynamic linear optical filter-in contrast to conventional static filters-with a shaping mask instantaneously adapting to the laser field.
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http://dx.doi.org/10.1038/s41598-020-72170-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7486391PMC
September 2020

Raman effect in the spectral broadening of ultrashort laser pulses in saturated versus unsaturated hydrocarbon molecules.

Opt Express 2020 Jan;28(2):980-990

A conventional hollow core fiber (HCF) scheme is implemented to investigate spectral broadening of Titanium:Sapphire (Ti-Sa) femtosecond laser pulses in saturated hydrocarbon molecules compared to unsaturated ones. While the saturated molecules exhibit a spectral broadening similar to noble gases, for the unsaturated ones with π bonds, broadening towards blue is restrained. Numerical simulations underpin that it is a combination of group velocity dispersion (GVD) and Raman scattering which limits the spectral broadening for the unsaturated molecules. Compression of low energy ∼40fs pulses to ∼8fs using saturated hydrocarbons is demonstrated, suggesting the feasibility of this media for high repetition rate laser pulse compression.
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http://dx.doi.org/10.1364/OE.380941DOI Listing
January 2020

Temporal characterization of femtosecond laser pulses using tunneling ionization in the UV, visible, and mid-IR ranges.

Sci Rep 2019 Nov 5;9(1):16067. Epub 2019 Nov 5.

Center for Relativistic Laser Science, Institute for Basic Science, Gwangju, 61005, Korea.

To generalize the applicability of the temporal characterization technique called "tunneling ionization with a perturbation for the time-domain observation of an electric field" (TIPTOE), the technique is examined in the multicycle regime over a broad wavelength range, from the UV to the IR range. The technique is rigorously analyzed first by solving the time-dependent Schrödinger equation. Then, experimental verification is demonstrated over an almost 5-octave wavelength range at 266, 1800, 4000 and 8000 nm by utilizing the same nonlinear medium - air. The experimentally obtained dispersion values of the materials used for the dispersion control show very good agreement with the ones calculated using the material dispersion data and the pulse duration results obtained for 1800 and 4000 nm agree well with the frequency-resolved optical gating measurements. The universality of TIPTOE arises from its phase-matching-free nature and its unprecedented broadband operation range.
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http://dx.doi.org/10.1038/s41598-019-52237-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6831698PMC
November 2019

Molecular gases for pulse compression in hollow core fibers.

Opt Express 2018 Sep;26(19):25426-25436

We introduce hydrofluorocarbon molecules as an alternative medium to noble gases with low ionization potential like krypton or xenon to compress ultrashort pulses of relatively low energy in a conventional hollow core fiber with subsequent dispersion compensation. Spectral broadening of pulses from two different laser systems exceeded those achieved with argon and krypton. Initially 40 fs, 800 nm, 120 μJ pulses were compressed to few optical cycles duration. With the same approach a compression factor of more than 10 was demonstrated for an ytterbium-based laser (1030 nm, 170 fs, 200 μJ) leading to 15.6 fs.
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http://dx.doi.org/10.1364/OE.26.025426DOI Listing
September 2018

Study of middle infrared difference frequency generation using a femtosecond laser source in LGT.

Opt Lett 2017 Sep;42(18):3698-3701

We demonstrate phase-matched difference frequency generation in the emerging nonlinear crystal LaGaTaO. Tunable wavelengths between 1.4 and 4.7 μm are generated by using femtosecond sources. We also report on the measurements of the optical damage threshold in the femtosecond regime and on the nonlinear refractive index n.
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http://dx.doi.org/10.1364/OL.42.003698DOI Listing
September 2017

Decoupling Frequencies, Amplitudes and Phases in Nonlinear Optics.

Sci Rep 2017 08 11;7(1):7861. Epub 2017 Aug 11.

INRS-EMT, 1650 Blvd. Lionel Boulet, Varennes, J3X1S2, Qc, Canada.

In linear optics, light fields do not mutually interact in a medium. However, they do mix when their field strength becomes comparable to electron binding energies in the so-called nonlinear optical regime. Such high fields are typically achieved with ultra-short laser pulses containing very broad frequency spectra where their amplitudes and phases are mutually coupled in a convolution process. Here, we describe a regime of nonlinear interactions without mixing of different frequencies. We demonstrate both in theory and experiment how frequency domain nonlinear optics overcomes the shortcomings arising from the convolution in conventional time domain interactions. We generate light fields with previously inaccessible properties by avoiding these uncontrolled couplings. Consequently, arbitrary phase functions are transferred linearly to other frequencies while preserving the general shape of the input spectrum. As a powerful application, we introduce deep UV phase control at 207 nm by using a conventional NIR pulse shaper.
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http://dx.doi.org/10.1038/s41598-017-07510-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5554166PMC
August 2017

Laser-assisted guiding of electric discharges around objects.

Sci Adv 2015 Jun 19;1(5):e1400111. Epub 2015 Jun 19.

Institut National de la Recherche Scientifique-Énergie Matériaux Télécommunications, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada. ; Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.

Electric breakdown in air occurs for electric fields exceeding 34 kV/cm and results in a large current surge that propagates along unpredictable trajectories. Guiding such currents across specific paths in a controllable manner could allow protection against lightning strikes and high-voltage capacitor discharges. Such capabilities can be used for delivering charge to specific targets, for electronic jamming, or for applications associated with electric welding and machining. We show that judiciously shaped laser radiation can be effectively used to manipulate the discharge along a complex path and to produce electric discharges that unfold along a predefined trajectory. Remarkably, such laser-induced arcing can even circumvent an object that completely occludes the line of sight.
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http://dx.doi.org/10.1126/sciadv.1400111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4640611PMC
June 2015

Efficient spectral-step expansion of a filamenting laser pulse.

Opt Lett 2013 May;38(9):1576-8

Defence R&D Canada Valcartier, Québec (Qc), Canada.

We report an efficient transfer of 800 nm energy into both the ultraviolet and the far infrared (IR) during the filamentation in air of an appropriately shaped laser pulse. The multiorder enhancement of the IR supercontinuum in the 3-5 μm atmospheric transmission windows was achieved thanks to spectral-step cascaded four-wave mixing occurring within the spectrum of the shaped femtosecond laser pulse. These results also point out the limit of the self-phase modulation model to explain the spectral broadening of a filamenting laser pulse.
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http://dx.doi.org/10.1364/OL.38.001576DOI Listing
May 2013

Charge resonance enhanced ionization of CO2 probed by laser Coulomb explosion imaging.

Phys Rev Lett 2011 Aug 2;107(6):063201. Epub 2011 Aug 2.

J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, 66503, USA.

The process by which a molecule in an intense laser field ionizes more efficiently as its bond length increases towards a critical distance R(c) is known as charge resonance enhanced ionization (CREI). We make a series of measurements of this process for CO(2), by varying pulse duration from 7 to 200 fs, in order to identify the charge states and time scales involved. We find that for the 4+ and higher charge states, 100 fs is the time scale required to reach the critical geometry ≈ 2.1 Å and <θ(OCO)> ≈ 163° (equilibrium CO(2) geometry is ≈ 1.16 Å and <θ(OCO)> ≈ 172°). The CO(2)(3+) molecule, however, appears always to begin dissociation from closer than 1.7 Å indicating that dynamics on charge states lower than 3+ is not sufficient to initiate CREI. Finally, we make quantum ab initio calculations of ionization rates for CO(2) and identify the electronic states responsible for CREI.
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http://dx.doi.org/10.1103/PhysRevLett.107.063201DOI Listing
August 2011

CEP stable 1.6 cycle laser pulses at 1.8 μm.

Opt Express 2011 Mar;19(7):6858-64

Institut National de la Recherche Scientifique, Centre Energie Matériaux et Télécommunications, Varennes, QC, Canada.

By using the novel approach for pulse compression that combines spectral broadening in hollow-core fiber (HCF) with linear propagation in fused silica (FS), we generate 1.6 cycle 0.24 mJ laser pulses at 1.8 μm wavelength with a repetition rate of 1 kHz. These pulses are obtained with a white light seeded optical parametric amplifier (OPA) and shown to be passively carrier envelope phase (CEP) stable.
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http://dx.doi.org/10.1364/OE.19.006858DOI Listing
March 2011

Pulse compression and shaping of broadband optical parametric amplifier laser source.

Opt Lett 2008 Dec;33(23):2824-6

Institut National de la Recherche Scientifique, Centre Energie Matériaux et Télécommunications, 1650 Boulevard Lionel-Boulet, Varennes, QC J3X1S2, Canada.

We report pulse compression and shaping of a 100 Hz broadband optical parametric amplifier (OPA) laser source generated by self-phase modulation in a hollow-core fiber. The amplitude and phase of the broadband OPA laser pulses are controlled using an acousto optic programmable dispersive filter (AOPDF). Using the AOPDF, we demonstrate compression, characterization, and amplitude/phase control of 1300 nm 20 fs laser pulses with energies up to 10 microJ. This novel source is suitable for seeding successive OPA amplification stages and for time-resolved spectroscopy.
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http://dx.doi.org/10.1364/ol.33.002824DOI Listing
December 2008