Experimental and Theoretical Studies of Phase Modulation in Yb-doped Fiber Amplifiers

We present detailed studies of the effect of sinusoidal phase modulation on stimulated Brillouin scattering (SBS) in ytterbium-doped fiber amplifiers. Based on a time-dependent SBS model, SBS enhancement factor versus pump linewidth for different modulation depths ranging from 0 to, and modulation frequencies ranging from 30 MHz to 500 MHz were analyzed. In addition, experimental validation of SBS suppression via sinusoidal phase modulation is presented with experimental results agreeing well with the model and simulations. Furthermore, narrow linewidth coherent beam combining (CBC) of 5 sinusoidal phase modulated lasers is demonstrated via LOCSET. Presented at SPIE Defense and Security 2012, Baltimore, MD on 23-27 Apr 2012. Accepted for publication in Laser Technololgy for Defense and Security VIII, the SPIE Proceedings Volume 8381, article 83811B1, 2012. The original document contains color images.