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.

Terahertz time-domain reflectometry applied to the investigation of hidden mural paintings

Abstract: Terahertz time-domain reflectometry has been used to investigate hidden layers of mural paintings. Images of graphite underdrawings and dielectric paint patterns have been resolved through plaster. The reflectivity of several historical paint pigments were compared.

Coherent acceleration by laser pulse echelons in periodic plasma structures

Abstract: We consider a possibilty to use an echelon of mutually coherent laser pulses generated by the emerging CAN (Coherent Amplification Network) technology for direct particle acceleration in periodic plasma structures We discuss resonant and free streaming configurations The resonant plasma structures can trap energy of longer laser pulses but are limited to moderate laser intensities of about 1014 W/cm2 and are very sensitive to the structure quality The free streaming configurations can survive laser intensities above 1018 W/cm2 for several tens of femtoseconds so that sustained accelerating rates well above TeV/m are feasible In our full electromagnetic relativistic particle-in-cell (PIC) simulations we show a test electron bunch gaining up to 200 GeV over a distance of 102 cm only

VIA-2 Characterization of TEGFET's and MESFET's using the electrooptic sampling technique

Abstract: Recent advances in GaAs technology have resulted in several new classes of devices, all of which have very high speed response [1,2]. These devices have been shown, indirectly, to have response times of tens of picoseconds [1]. Indirect measurements are necessary because available sampling oscilloscopes have a limiting response of 25 picoseconds and jitter of a few picoseconds. Hence, most ultrafast devices are characterized in a ring oscillator configuration of several devices and individual device response is averaged. In the frequency domain most RF measurements are connector limited to the range of 18 GHz.

Low-Temperature Epitaxially Grown GaAs as a High-Speed Photoconductor for Terahertz Spectroscopy,

Abstract: : Photoconductive elements have been employed to generate and detect ultrafast electrical signals in many areas of optical electronics. One outstanding application of these structures, when they are fabricated on substrates with rapid recombination times, is as transmitting and receiving antennas that can be used for millimeter-wave and submillimeter-wave spectroscopy. Experiments which characterize a terahertz radiation system using dipole-like antennas have been carried out, and the system has been applied to the spectroscopy of dielectrics and semiconductors. Assuming that short laser pulses and a high quality imaging system are available, the fidelity of the broadcast signals and the resolution attainable for a spectroscopy system depend primarily on the photoconductor material and antenna system.

Terahertz investigation of Egyptian artifacts

Abstract: THz Time Domain Spectroscopy can be use to image optically opaque objects or detect different materials. It is a non-destructive, non-ionizing and non-contact measurement technique. We propose to use terahertz to analyze different models of Egyptian papyrus. By using the ink parameters we demonstrate the possibility to image multilayer papyrus distant by 500 μm.

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.