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Petawatt Reflective Optics

Different Petawatt class lasers are in operation or in development around the world. In such systems, in order to limit the accumulation of non-linear effects related to the propagation of intense pulses, reflective optics are used at the end of the chain and are illuminated by very high power densities: compression gratings, transport mirrors, focusing parabola.
The phenomenon of laser damage is the main parameter limiting the power accessible by these lasers. It is necessary to understand and control this phenomenon in order to make a laser installation more reliable and also to improve their performances. In this framework and through various academic and industrial collaborations, we work on different axes of studies to understand these issues and improve the laser damage resistance of the optics:

ILM - REOSC picture
Picture of a 800 mm 90-deg off-axis parabola with a high laser resistance coating for multi-PW laser systems

 Study of the laser damage resistance of materials that can be used for the manufacture of reflective optics
 Design of reflective optics by decreasing the strengthening of the electric field in structures, one of the main causes of laser damage.
 Metrology of laser damage in short pulse regime with the development of adapted test procedures, especially to quantify the limiting defects, the phenomena of fatigue and growth of damage under multiple shots.
 Study of the physics of the initiation and growth of laser damage to develop predictive models and for the improvement of the optics used on laser chain.

Contact : Laurent Gallais

Recent Publications:

 Hervy A., Gallais L., Chériaux G., Mouricaud D., ‘Femtosecond laser-induced damage threshold of electron beam deposited dielectrics for 1-m class optics’, Optical Engineering 56, 011001 (2017). http://dx.doi.org/10.1117/1.OE.56.1.011001
 Sozet M., Neauport J., Lavastre E., Roquin N., Gallais L., Lamaignere L.,’Laser damage growth with picosecond pulses’, Optics Letters, 41 2342 (2016). http://dx.doi.org/10.1364/OL.41.002342
 Sozet M., Neauport J., Lavastre E., Roquin N., Gallais L., Lamaignere L.,’Assessment of mono-shot measurement as a fast and accurate determination of the laser-induced damage threshold in the sub-picosecond regime’, Optics Letters, 41 804 (2016). http://dx.doi.org/10.1364/OL.41.000804
 Nagy B.J., Gallais L., Vamos L., Oszetzky D., Racz P., Dombi P., ’Direct comparison of kilohertz- and megahertz-repetition-rate femtosecond damage threshold’, Optics Letters, 40 2091 (2015). http://dx.doi.org/10.1364/OL.40.002525
 Sozet M., Neauport J., Lavastre E., Roquin N., Gallais L., Lamaignere L., ’Laser damage density measurement of optical components in the sub-picosecond regime’, Optics Letters, 40 2091 (2015). http://dx.doi.org/10.1364/OL.40.002091