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

fYear

2007

fDate

17-22 June 2007

Firstpage

1

Lastpage

1

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;

fLanguage

English

Publisher

ieee

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

Type

conf

DOI

10.1109/CLEOE-IQEC.2007.4386366

Filename

4386366