Fyzikální ústav Akademie věd ČR

The basic task of the Department of Nonlinear optics is research and development of a unique method of the amplification of ultrashort laser pulses OPCPA (Optical Parametric Chirped Pulse Amplification). On this matter the Department closely cooperates with the Laser Plasma Research Center PALS. The OPCPA method will allow for increasing the output power of the PALS laser from terawatt to petawatt level by 1000-times compressing the laser pulse. These pulses are and will be used partly for the basic research of the interaction of optical field and matter and partly for medical and industry applications. This research follows the actual trends in the ultraintense and ultrashort laser pulse physics.

To meet the demands of the method two laser beams were built-up, so-called signal and pump, and their very precise time and spatial synchronization in a nonlinear optical crystal was developed. A low power spectrally broadband Ti:Sapphire laser beam is used as signal beam. The signal is stretched from femtoseconds to hundreds of picoseconds by a grating stretcher. Then it impinges the nonlinear optical crystal under a definite angle at exactly the same time as the strong pump beam. In our case the pump beam is the iodine photodissociation laser beam SOFIA (Solid-state Oscillator Followed by Iodine Amplifiers). The energy of the pump beam is transferred to the signal beam during the parametric amplification process inside the optical crystal. So the signal beam is very strong and broad band (its former property) after leaving the crystal. The signal beam then passes a grating compressor where the pulse length is compressed to its almost original length (femtoseconds). Its power (energy / time) is very high now.

The iodine laser provides high energy in one homogenous laser beam, therefore is very suitable for the OPCPA technique. In the test laboratory SOFIA the build-up of the signal and pump beams is finished, and the OPCPA experiments have started.

Master and PhD students of the Faculty of Nuclear Sciences and Physical Engineering, CTU, Prague, have major share on this challenging development of signal and pump beams in the laboratory SOFIA. They have chance to get educated in technique and physics of high power lasers in a well-equipped laboratory.