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.

120-GHz-Bandwidth Characterization of Microwave Passive Devices Using External Silicon-On-Sapphire Photoconductive Sampling Probe

Abstract: Conventional purely electronic measurement instruments such as vector network analyzers, spectrum analyzers and sampling oscilloscopes are not effective at above 100 GHz. One major limitation is imposed by the connectors and waveguides needed for signal coupling between the test instrument and the device under test. To overcome those limitations of present measurement techniques, we have developed a photoconductive probe sampling technique which can be applied to the measurement of S-parameters of mm- wave circuit components with a 120-GHz measurement bandwidth [1]. The photoconductive probe sampling technique combines the ultrafast optical technology of 120-fs Ti-Sapphire short pulse laser [2] and microfabrication technology of Silicon-On-Sapphire (SOS) photoconductive sampling probe, which consists of a high-impedance interdigitated photoconductive switch. The probe technology has demonstrated a 2.1 ps temporal resolution and low-invasiveness making this very attractive for external circuit testing of mm-wave circuits with a 120-GHz measurement bandwidth.

Heuristic laser device using an apparatus for producing laser pulses, and corresponding heuristic method

Abstract: A laser device includes an apparatus for producing amplified laser pulses, using a plurality of amplifying optical fibers, and groups the basic amplified pulses into an overall amplified pulse, as well as a target, onto which the overall amplified pulse is directed such as to generate a predetermined physical process thereon, which causes a change of state in the target. The laser device is configured to measure at least one distinctive parameter of the generated physical process; adjust at least one characteristic for adjusting the basic amplified laser pulses; and analyze a plurality of measurements for different adjustments. The device analyzes the measurements many times in loops for different laser pulse adjustment characteristics, enabling an optimization by a heuristic method. Also provided is a heuristic optimization method implemented by the laser device.

Tunneling-Time Measurements of a Resonant Tunneling Diode

Abstract: Tunneling-time measurements on a heterojunction double-barrier resonant tunneling diode (RTD) have been made using electro-optic sampling techniques. Quantum- mechanical tunneling in these single quantum wells is the fastest known charge-transport mechanism in semiconductors. This class of device exhibits such features as negative differential resistance (NDR), an extremely fast current response,1 and a high-frequency output when applied as an oscillator.2 Now, using a laser-based sampling system having a demonstrated subpicosecond temporal response,3 a switching time of less than 2 ps has been measured for a double-barrier RTD. This measurement indicates the potential utility of these diodes as high-speed logic devices4 and helps explain the tunneling mechanisms involved.

PetaVolts per meter Plasmonics: introducing extreme nanoscience as a route towards scientific frontiers

Abstract: A new class of plasmons has opened access to unprecedented PetaVolts per meter electromagnetic fields which can transform the paradigm of scientific and technological advances. This includes non-collider searches in fundamental physics in addition to making next generation colliders feasible. PetaVolts per meter plasmonics relies on this new class of plasmons uncovered by our work in the large amplitude limit of collective oscillations of quantum electron gas. This Fermi gas constituted by “free” conduction band electrons is inherent in conductive media endowed with a suitable combination of constituent atoms and ionic lattice structure. As this quantum gas of electrons can be as dense as 1024 cm-3, the coherence limit of plasmonic electromagnetic fields is extended in our model from the classical to the quantum domain, 0.1 √(n 0(1024 cm-3)) PVm-1. Appropriately engineered, structured materials that allow highly tunable material properties also make it possible to overcome disruptive instabilities that dominate the interactions in bulk media. The ultra-high density of conduction electrons and the existence of electronic energy bands engendered by the ionic lattice is only possible due to quantum mechanical effects. Based on this framework, it is critical to address various challenges that underlie PetaVolts per meter plasmonics including stable excitation of plasmons while accounting for their effects on the ionic lattice and the electronic energy band structure over femtosecond timescales. We summarize the challenges and ongoing efforts that set the strategy for the future. Extreme plasmonic fields can shape the future by not only opening the possibility of tens of TeV to multi-PeV center-of-mass-energies but also enabling novel pathways in non-collider HEP. In view of this promise, our efforts are dedicated to realization of the immense potential of PV/m plasmonics and its applications.

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.