Superstrong field science

Over the past fifteen years we have seen a surge in our ability to produce high intensities, five to six orders of magnitude higher than was possible before. At these intensities, particles, electrons and protons, acquire kinetic energy in the mega-electron-volt range through interaction with intense laser fields. This opens a new age for the laser, the age of nonlinear relativistic optics coupling even with nuclear physics. We suggest a path to reach an extremely high-intensity level 1026–28 W/cm21026–28W/cm2 in the coming decade, much beyond the current and near future intensity regime 1023 W/cm2,1023W/cm2, taking advantage of the megajoule laser facilities. Such a laser at extreme high intensity could accelerate particles to frontiers of high energy, tera-electron-volt and peta-electron-volt, and would become a tool of fundamental physics encompassing particle physics, gravitational physics, nonlinear field theory, ultrahigh-pressure physics, astrophysics, and cosmology. Such a laser intensity may also be very beneficial to an alternative, more direct approach of fast ignition in laser fusion. We suggest a new possibility to explore this. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87922/2/423_1.pd

FORUM on superstrong fields and high energy physics

© 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87923/2/459_1.pd

Ultrahigh intensity laser for laser wakefield acceleration

The next generation of high peak power CPA laser systems will be improved in compactness, simplicity, and cost. Yb:glass is a suitable choice for the amplifier medium in such a laser system necessary for an all-optical GeV accelerator. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87564/2/68_1.pd

Radiation back-reaction in relativistically strong and QED-strong laser fields

The emission from an electron in the field of a relativistically strong laser pulse is analyzed. At the pulse intensities of \ge 10^{22} W/cm^2 the emission from counter-propagating electrons is modified by the effects of Quantum ElectroDynamics (QED), as long as the electron energy is sufficiently high: E \ge 1 GeV. The radiation force experienced by an electron is for the first time derived from the QED principles and its applicability range is extended towards the QED-strong fields.Comment: 4 pages, 4 figure

1.4 ps rise‐time high‐voltage photoconductive switching

We report on the generation of 825 V electrical pulses with 1.4 ps rise time and 4.0 ps duration using a pulse‐biased low‐temperature‐grown GaAs photoconductive switch triggered by an amplified femtosecond dye laser. Dependence of the pulse shape on both electric field and optical energy is observed and discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70925/2/APPLAB-59-12-1455-1.pd

Subpicosecond photoresponse of carriers in low‐temperature molecular beam epitaxial In0.52Al0.48As/InP

Femtosecond time‐resolved reflectivity and photoconductive switching measurements have been made of In0.52Al0.48As grown by molecular beam epitaxy on (100) InP substrates at growth temperatures ranging from 150 to 480 °C. A response/switching time of ∼400 fs is measured in the sample grown at 150 °C. Temperature‐dependent measurements shed light on the nature of the material producing the ultrafast response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71065/2/APPLAB-57-15-1543-1.pd

Optical properties of high‐quality InGaAs/InAlAs multiple quantum wells

We have measured the narrowest half‐width at half‐maximum photoluminescence linewidth of 2.8 meV, in 40‐period lattice‐matched In0.53Ga0.47As/In0.52Al0.48As multiple quantum wells, grown by molecular‐beam epitaxy with growth interruption. A simple analysis of the linewidth suggests that the structure has near perfect interfaces. Temperature‐dependent photoluminescence linewidth data indicate impurity incorporation due to the growth interruption. However, the high quality of the multiple quantum well is not impaired as is seen in the room‐temperature absorption data, where excitonic features up to n=3 sublevel are clearly seen. Carrier lifetime in this multiple‐quantum‐well system has been measured, we believe for the first time, using the picosecond photoluminescence correlation technique. A lifetime of 860 ps is obtained, which is similar to the value obtained for high‐quality GaAs/AlGaAs and In0.53Ga0.47As/InP quantum wells. This further confirms the high quality obtained in this ternary material system using growth interruption.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70406/2/JAPIAU-69-5-3219-1.pd

Reduction of multi-photon ionization in dielectrics due to collisions

The collisional effect due to the multi-photon ionization process in dielectric material has been studied. We found that the breakdown threshold of fused silica is the same for both linearly and circularly polarized light at 55 fs and 100 fs, which we believe is an indication of the suppression of multi-photon ionization in solids. By numerically solving the time-dependent Schrödinger equation with scattering, for the first time, we have observed substantial reduction of the multi-photon ionization rate in dielectrics due to collisions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47043/1/340_2005_Article_BF01831002.pd

Subpicosecond time‐resolved studies of coherent phonon oscillations in thin‐film YBa2Cu3O6+x (x<0.4)

We report the results of the first time‐resolved observation of impulsively generated coherent optical phonon oscillations in the semiconducting cuprate compound YBa2Cu3O6+x (x<0.4). The oscillations, which were probed through time‐resolved transmissivity modulation, had a period of 237 fs at room temperature, corresponding to a Raman active mode of A1g symmetry at 142 cm−1. No oscillations were observed in the superconducting form of Y‐Ba‐Cu‐O either above or below Tc. The amplitude, frequency, and linewidth of this mode were measured over a temperature range from ∼7 K to room temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70769/2/APPLAB-58-9-980-1.pd

Single-pulse Laue diffraction, stroboscopic data collection and femtosecond flash photolysis on macromolecules

We review the time structure of synchrotron radiation and its use for fast time-resolved diffraction experiments in macromolecular photo-cycles using flash photolysis to initiate the reaction. The source parameters and optics for ID09 at ESRF are presented together with the phase-locked chopper and femtosecond laser. The chopper can set up a 900 Hz pulse train of 100 ps pulses from the hybrid bunch-mode and, in conjunction with a femtosecond laser, it can be used for stroboscopic data collection with both monochromatic and polychromatic beams. Single-pulse Laue data from Cutinase, a 22 kD lipolic enzyme, are presented which show that the quality of single-pulse Laue patterns is sufficient to refine the excited state(s) in a reaction pathway from a known ground state. The flash photolysis technique is discussed and an example is given for heme proteins. The radiation damage from a laser pulse in the femto and picosecond range can be reduced by triggering at a wavelength where the interaction is strong. We propose the use of microcrystals between 25–50 μm for efficient photolysis with femto and picosecond pulses. The performance of circular storage rings is compared with the predicted performance of an X-ray free electron laser (XFEL). The combination of micro beams, a gain of 105105 photons per pulse and an ultrashort pulse length of 100 fs is likely to improve pulsed diffraction data very substantially. It may be used to image coherent nuclear motion at atomic resolution in ultrafast uni-molecular reactions. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87418/2/267_1.pd