Statistical properties of the monochromatic laser radiation partially depleted through the stimulated Brillouin scattering in a single mode optical fiber. Andrei A. Fotiadi*, Patrice Mégret, Michel Blondel Service d'Electromagnétisme et de Télécommunications, Faculté Polytechnique de Mons, 31 Boulevard Dolez, B-7000, Mons, Belgium Tel: +32 65 374198; Fax: +32 65 374199; E-mail: Fotiadi@telecom.fpms.ac.be *Also with Ioffe Physico-Technical Institute of RAS, St.Petersburg, Russia We performed numerical simulations in order to explore statistical properties of the monochromatic laser radiation partially depleted through the stimulated Brillouin scattering process in a single mode optical fiber. We give a clear physical insight into the problem and, for what is to our knowledge the first time, reveal how the probability function of the transmitted laser power evolves as key parameters of the model vary, leading to a modification of Stokes field statistics. Introduction Stochastic fluctuations of the scattered Stokes power as well as similar fluctuations of the pump power transmitted through the fiber (residual power) are commonly recorded in SBS experiments [1]. Initiated by spontaneous noise these fluctuations can be observed even under CW excitation of the fiber by a well-stabilized monochromatic pump. We have already reported [2] statistical properties of the scattered Stokes radiation. A Stokes power probability function has been described for a wide range of SBS regimes. We explored nontrivial evolution of the Stokes field statistics above the SBS threshold and demonstrated that modification of the Stokes field statistics is responsible for broadening and hole burning of the spectra of SBS power observed in the experiment [3]. Whereas it has already been done for Stokes signals, the statistics of the pump field transmitted trough the fiber has not been investigated yet and is reported here for the first time. Concretely, we reveal how the probability function of the pump power evolves as the key parameters of a one-dimensional SBS model vary, leading to the modification of the Stokes field statistics. To complete the picture these new results are presented in conjugation with corresponding data related to the Stokes radiation. Our interest to the problem is warmed up by recent observations of the residual pump power spectra [4]. SBS model and numerical procedure Numerical simulations were based on the set of one-dimensional SBS dynamical equations for complex amplitudes of the pump wave ( ) , L E zt , the Stokes wave ( ) , S E zt and the hypersound wave [1]. Boundary conditions correspond to the injection of a monochromatic CW pump wave at ( , zt ρ ) 0 z = , i.e. ( ) 0 0, L E t P = , Other parameters in the calculations are related to SBS in typical telecommunication fiber at pump wavelength of ( ) , S E Lt = 0. ~1 L m λ µ : 9 2.5 10 g c − = ⋅ mW ns m is SBS gain, is the acoustic phonon lifetime, 2 10 T = 2 25 S µ = is the fiber mode area. The initiating noise was