The laser design is based on a hybrid architecture.
The front-end relies on the optical parametric chirped pulse amplification (OPCPA) technology. The chosen design allows delivering - at a repetition rate higher than 20 Hz - ~30 mJ in more than 1 ns, with a spectral bandwidth compatible with a duration of 10 fs after compression.
► Amplifying stages
APOLLON has 4 consecutive amplifying stages to reach a pulse energy of 140 J (with the current available ressources); gain broadening is kept low enough to ensure, after compression, a duration of 15 fs, for a compressed energy of 75 J, i.e. 5 PW. The chosen amplifying medium is titanium-doped sapphire. In the last 2 stages (30 J and 140 J), the crystals are pumped by a Thalès ATLAS laser (delivering 100 J at 527 nm) and by the CNE400 laser, developed by Continuum (Amplitudes Technologies) and delivering 650 J in the IR and 400 J after frequency doubling.
► Compression & transport
Several optical systems are implemented to control the final performances of the system (in terms of pulse duration and contrast). An Öffner-type stretcher allows extending the front-end pulse duration from 10 ps to 1 ns and delivering a spectral bandwidth of 200 nm, with minimal aberrations. A local compressor, in air, allows compressing part (~ 10 mJ) of the front-end output to monitor the compression process (in terms of duration and contrast) prior to amplification. After amplication, a vacuum compressor allows reaching a duration of 15 fs, for an output energy of 150 J, i.e. 5 PW ("F1" beam); a monolithic scheme using 4 910 x 455 mm2 gratings is used.
► Control-command & supervision
The APOLLON control system (C2S) d'APOLLON shall cover the needs of the current and future operators and users. It has been designed to (i) ensure the staff safety, (ii) distribute the required timing triggers, (iii) provide the functional features to operate, supervise and protect the machine, (iv) acquire the laser and experimental data and (v) manage the corresponding databases and provide to the users the adequate interfaces. The Tango system has been chosen and was officially commissioned in Spring 2011.
► APOLLON CAD-based digital mock-up