<title>Forward and backward cascaded stimulated Brillouin scattering in a S band distributed G652 fiber Raman amplifier</title>

Abstract

The forward and backward cascaded stimulated Brillouin scattering (SBS) in the backward pumped S band distributed G652 fiber Raman amplifier have been researched, pumped by the tunable power 1428nm fiber Raman laser and signal source is a tunable narrow spectral bandwidth (<100MHz)ECL. The forward SBS does not obey the common theory, that only weaken backward-SBS lines existed, according to conservation of energy and momentum and wave vector selected rule. Because the wave-guide character weaken the wave vector rule, the forward transmit sound wave-guide forward Brillouin scattering lines are generated and amplified in S band G652 FRA. Forward SBS that is amplified phenomena of transmit sound wave Brillouin scattering in the G652 FRA, during pump power is larger than the threshold value of SBS in a S band G652 FRA. Two-order SBS in the Stokes region is observed during the pump power is increased. When the FRA pump power is further increased, Cascaded SBS lines and comb profile are observed.