Gerard Mourou

Bio: Gerard Mourou is an academic researcher from École Polytechnique. The author has contributed to research in topics: Laser & Ultrashort pulse. The author has an hindex of 82, co-authored 653 publications receiving 34147 citations. Previous affiliations of Gerard Mourou include University of Michigan & San Diego State University.

Electro-Optic Sampler for Characterization of Devices in a Cryogenic Environment

Abstract: A fully integrated superconducting electro-optic sampler, designed for subpicosecond measurements of the transient response of devices operating in a cryogenic environment, is reviewed in detail. Several different configurations of the sampling head, including a coplanar transmission line geometry with a photoconductive switch fabricated on semi-insulating GaAs and sensor transmission lines fabricated on lithium tantalate, are discussed. The optical part of the system consists of two 80-fs laser pulse trains at a 100 MHz repetition rate, generated by a colliding-pulse mode-locked laser. One pulse train was used to generate a picosecond electrical input pulse, while the second probed the induced change in birefringence of the electro-optic crystal (LiTaO3). By changing the relative delay between the optical excitation and sampling pulses, the temporal evolution of the electrical transient was recorded. The limit of the temporal response of our sampler, as determined by measuring the transient onset of photoconductivity in a GaAs switch, was less than 400 fs. We discuss two applications of this sampler for the study of the picosecond pulse propagation on superconducting transmission lines and for probing the switching of a Josephson tunnel junction.

A Passion for extreme light

Abstract: Extreme-light laser is a universal source providing a vast range of high energy radiations and particles along with the highest field, highest pressure, temperature and acceleration. It offers the possibility to shed light on some of the remaining unanswered questions in fundamental physics like the genesis of cosmic rays with energies in excess of 1020 eV or the loss of information in black-holes. Using wake-field acceleration some of these fundamental questions could be studied in the laboratory. In addition extreme-light makes possible the study of the structure of vacuum and particle production in "empty" space which is one of the field’s ultimate goal, reaching into the fundamental QED and possibly QCD regimes. Looking beyond today’s intensity horizon, we will introduce a new concept that could make possible the generation of attosecond-zeptosecond high energy coherent pulse, de facto in x-ray domain, opening at the Schwinger level, the zettawatt, and PeV regime; the next chapter of laser-matter interaction.

Development of novel ultrafast-laser-based micro-CT system for small-animal imaging

Abstract: We investigated the performance of an ultrafast-laser-based X-ray source as a possible replacement of a microfocal X-ray tube in a micro-CT system for small-animal imaging. Using a number of solid targets (Ge, Mo, Ag, Sn, BaF/sub 2/, La, and Nd) with matching filters, we optimized conditions for X-ray generation and measured X-ray spectra, conversion efficiency, X-ray fluence, and X-ray focal-spot size. We obtained images of small animals. X-ray spectra created by ultrafast laser are advantageous for micro-CT imaging because most of the emission is in narrow characteristic lines. The spectra could be rapidly changed and matched to the imaging task (e.g. animal thickness and density). This novel X-ray source can be also easily applied in dual-energy micro-CT for small-animal imaging with suitable contrast agent (e.g. I-, Ba-, or Gd-based) and matching targets and filters for low- and high-energy beams. We have established that the effective X-ray focal-spot size can be smaller than 5 /spl mu/ and that the average power can surpass the power delivered by a microfocal X-ray tube with 5 /spl mu/m focal-spot size.

“Cascade-Raman” soliton compression with 30-fs, Terawatt pulses

Abstract: Theoretically, Raman-like soliton compression of mJ, 30-fs pulses is predicted. Initial experiments demonstrate 2 times compression of 1.3 TW/cm2 pulses under non-optimal conditions. The results agree closely with numerical simulations.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

A roadmap for graphene

Abstract: Recent years have witnessed many breakthroughs in research on graphene (the first two-dimensional atomic crystal) as well as a significant advance in the mass production of this material. This one-atom-thick fabric of carbon uniquely combines extreme mechanical strength, exceptionally high electronic and thermal conductivities, impermeability to gases, as well as many other supreme properties, all of which make it highly attractive for numerous applications. Here we review recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.

Black Hole Explosions

Abstract: QUANTUM gravitational effects are usually ignored in calculations of the formation and evolution of black holes. The justification for this is that the radius of curvature of space-time outside the event horizon is very large compared to the Planck length (Għ/c3)1/2 ≈ 10−33 cm, the length scale on which quantum fluctuations of the metric are expected to be of order unity. This means that the energy density of particles created by the gravitational field is small compared to the space-time curvature. Even though quantum effects may be small locally, they may still, however, add up to produce a significant effect over the lifetime of the Universe ≈ 1017 s which is very long compared to the Planck time ≈ 10−43 s. The purpose of this letter is to show that this indeed may be the case: it seems that any black hole will create and emit particles such as neutrinos or photons at just the rate that one would expect if the black hole was a body with a temperature of (κ/2π) (ħ/2k) ≈ 10−6 (M/M)K where κ is the surface gravity of the black hole1. As a black hole emits this thermal radiation one would expect it to lose mass. This in turn would increase the surface gravity and so increase the rate of emission. The black hole would therefore have a finite life of the order of 1071 (M/M)−3 s. For a black hole of solar mass this is much longer than the age of the Universe. There might, however, be much smaller black holes which were formed by fluctuations in the early Universe2. Any such black hole of mass less than 1015 g would have evaporated by now. Near the end of its life the rate of emission would be very high and about 1030 erg would be released in the last 0.1 s. This is a fairly small explosion by astronomical standards but it is equivalent to about 1 million 1 Mton hydrogen bombs. It is often said that nothing can escape from a black hole. But in 1974, Stephen Hawking realized that, owing to quantum effects, black holes should emit particles with a thermal distribution of energies — as if the black hole had a temperature inversely proportional to its mass. In addition to putting black-hole thermodynamics on a firmer footing, this discovery led Hawking to postulate 'black hole explosions', as primordial black holes end their lives in an accelerating release of energy.

Materials for terahertz science and technology

Abstract: Terahertz spectroscopy systems use far-infrared radiation to extract molecular spectral information in an otherwise inaccessible portion of the electromagnetic spectrum. Materials research is an essential component of modern terahertz systems: novel, higher-power terahertz sources rely heavily on new materials such as quantum cascade structures. At the same time, terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules.