Biomedical subjects

Jean-Paul Chambaret

Publications and source records attributed to Jean-Paul Chambaret.

5 recordsLinked to original sources

PubMed2007

Design and demonstration of a high-energy booster amplifier for a high-repetition rate petawatt class laser system.

We have successfully developed a high-energy, high-repetition rate Ti:sapphire laser system that delivers 33 J before compression at 0.1 Hz. The final booster amplifier is based on a 100 mm diameter Ti:sapphire crystal pumped with 72 J of energy in six beams delivered by three frequency-doubled high-repetition rate Nd:glass lasers. This system is, to the best of our knowledge, the first demonstrated petawatt class laser system running at a high repetition rate.

Journal Article↗

PubMed2005

10(-10) temporal contrast for femtosecond ultraintense lasers by cross-polarized wave generation.

We take advantage of nonlinear properties associated with chi(3) tensor elements in BaF2 cubic crystal to improve the temporal contrast of femtosecond laser pulses. The technique presented is based on cross-polarized wave (XPW) generation. We have obtained a transmission efficiency of 10% and 10(-10) contrast with an input pulse in the millijoule range. This filter does not affect the spectral shape or the phase of the cleaned pulse. It also acts as an efficient spatial filter. In this method the contrast enhancement is limited only by the extinction ratio of the polarization discrimination device.

Journal Article↗

PubMed2004

Experimental evidence of 25-fs laser pulse distortion in singlet beam expanders.

We report the measurement of spatiotemporal distortions of an ultrashort pulse in singlet beam expanders. With a simple second-order autocorrelator the temporal broadening of the pulse from 23 to 40 fs, due to propagation time difference (PTD), is determined. The delay due to PTD between different parts of the beam is also measured. This effect was theoretically studied for the first time by Bor [J. Mod. Opt. 35, 1907 (1988)]. These experimental results are in good agreement with the calculations of a dedicated three-dimensional ray-tracing program developed to simulate the spatial and temporal transformation of femtosecond pulses in optical systems.

Journal Article↗

PubMed2004

High-efficiency, simple setup for pulse cleaning at the millijoule level by nonlinear induced birefringence.

Nonlinear elliptical polarization rotation is used to improve the contrast of femtosecond pulses by several orders of magnitude. Using nonlinear induced birefringence in air, we produced cleaned pulses with an energy of a few hundreds of microjoules. This technique presents several major advantages, such as convenience and stability of the setup. We investigated the phase profile required for obtaining high-energy pulses. No phase distortion is observed, and the spatial quality of the beam is preserved.

Journal Article↗

PubMed2004

Practicability of protontherapy using compact laser systems.

Protontherapy is a well-established approach to treat cancer due to the favorable ballistic properties of proton beams. Nevertheless, this treatment is today only possible with large scale accelerator facilities which are very difficult to install at existing hospitals. In this article we report on a new approach for proton acceleration up to energies within the therapeutic window between 60 and 200 MeV by using modern, high intensity and compact laser systems. By focusing such laser beams onto thin foils we obtained on target intensities of 6 x 10(19) W/cm2, which is sufficient to produce a well-collimated proton beam with an energy of up to 10 MeV. These results are in agreement with numerical simulations and indicate that proton energies within the therapeutic window should be obtained in the very near future using such economical and very compact laser systems. Hence, this approach could revolutionize cancer treatment by bringing the "lab to the hospital-rather than the hospital to the lab".

Biophysical Phenomena↗