Title :
Paradox in the measurement of FM to AM conversion in high power lasers
Author :
Penninckx, Denis ; Di-Nicola, Jean-Michel ; Gleyze, Jean-François ; Hocquet, Steve
Author_Institution :
CEA, Le Barp
Abstract :
High power lasers such as the Laser MegaJoule (LMJ) under construction near Bordeaux (France) require phase modulations of the pulses in order to smooth the beam and to avoid stimulated Brillouin scattering in large optics which may cause damages. For anti-Brillouin, the phase modulation chosen for the LMJ is a sine-wave at a frequency of 2 GHz and a modulation index of 7 inducing a spectral broadening of 32 GHz. For smoothing, the broadening is larger because the phase modulation is a 14.25 GHz sine-wave having a modulation index of 5. Anti-Brillouin is always activated while smoothing may be activated or not (see the optical spectral power distributions (SPD).
Keywords :
amplitude modulation; fibre lasers; frequency modulation; optical fibre polarisation; optical modulation; Bordeaux; FM to AM conversion; antiBrillouin method; frequency 2 GHz; frequency 32 GHz; high power lasers; laser megajoule; optical spectral power distributions; phase modulation; polarization-maintaining fibre laser source; smoothing method; stimulated Brillouin scattering; Frequency modulation; Modular construction; Nonlinear optics; Optical modulation; Optical pulses; Optical scattering; Phase modulation; Power lasers; Power measurement; Smoothing methods;
Conference_Titel :
Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on
Conference_Location :
Munich
Print_ISBN :
978-1-4244-0931-0
Electronic_ISBN :
978-1-4244-0931-0
DOI :
10.1109/CLEOE-IQEC.2007.4386366
