G. Darpentigny

Search for stimulated photon-photon scattering in vacuum

Abstract:We have searched for stimulated photon scattering in vacuum at a center of mass photon energy of 0.8 eV. The QED contribution to this process is equivalent to four wave mixing in vacuum. No evidence for scattering was observed. The corresponding upper limit of the cross-section is .

High dynamic range autocorrelation studies of a femtosecond Ti: sapphire oscillator and its relevance to the optimisation of chirped pulse amplification systems

Abstract We report on background-free intensity autocorrelation studies of sub-50 fs pulses from a Kerr lens mode-locked (KLM) Ti: sapphire laser over an intensity dynamic range of approximately 7 orders of magnitude. Results reveal the presence of a low intensity pedestal, at the 10 −5 level, which can be improved by incorporating a hard aperture in the cavity. We also present the results derived from a ray tracing code used to investigate the propagatin of pulses through a cylindrical mirror stretcher/compressor. The strong dependence of the residual pedestal level with initial pulse bandwidth and spectral clipping is discussed. The various limiting effects of both the seed oscillator and the stretcher/compressor on the final pedestal intensity level in the linear amplification regime are discussed.

Multi-pass amplification of sub-50 fs pulses up to the 4 TW level

Abstract We describe the design and operation of a 2-stage multi-pass Ti:sapphire amplifier laser system, which is optimised for a broad transmission bandwidth and incorporates a novel reflective spherical mirror pulse-stretcher. Output energies of 180 mJ after compression, and amplified bandwidths up to 30 nm are observed.

Amplification of femtosecond pulses up to 29 TW at 10 Hz in Ti:sapphire

We demonstrate a femtosecond laser chain that generates 20 TW at 10 Hz in less than 50 fs with focused intensities higher than 3 X 1019 W/cm2. This system is optimized for a broad transmission bandwidth and includes an aberration-free stretcher compressor.

Observation of Relativistic Self-Focusing, Self-Channeling and Filamentation of Multiterawatt Ultra-Short Laser Pulses in Optical-Field Ionized Argon Gas Jets

Relativistic self-focusing, self-channeling and filamentation are observed in the propagation of a 50 fs, 5 TW laser pulse in an underdense Argon plasma.

Generation of 40 fs, 20 TW pulses at 10 Hz

We demonstrate a femtosecond laser chain that generates 20 TW at 10 Hz in less than 50 fs with focused intensities higher than 3x10^19 W/cm². This system is optimised for a broad transmission bandwidth and includes an aberration-free stretcher compressor.