Compensation of frequency modulation to amplitude modulation conversion in frequency conversion systems.
Frequency modulation to amplitude modulation (FM-to-AM) conversion is an important issue that can prevent fusion ignition with high power lasers such as the Laser MegaJoule (LMJ). On LMJ, most of the FM-to-AM conversion is expected in the so-called frequency conversion and focusing system, which is a nonlinear system. However, we propose linear transfer functions to compensate the effect of frequency conversion on FM-to-AM conversion. We show that most of AM distortion can be reduced by practical systems: for beam intensity up to 3 GW/cm(2), the FM-to-AM conversion level can be divided by at least 2, and we almost cancel intensity modulation for intensities below 1 GW/cm(2).
Commissariat à l'Energie Atomique/Centre d'études scientifiques et techniques d'Aquitaine, 15 avenue des sablières, BP 2, 33114 Le Barp, France. steve.hocquet@cea.fr
Steve
S
Hocquet
Geoffrey
G
Lacroix
Denis
D
Penninckx