Langevin description of speckle dynamics in nonlinear disordered media

摘要: We formulate a Langevin description of dynamics speckle pattern resulting from the multiple scattering coherent wave in nonlinear disordered medium. The exhibits instability with respect to periodic excitations at frequencies $\ensuremath{\Omega}$ below some ${\ensuremath{\Omega}}_{\mathrm{max}},$ provided that nonlinearity exceeds $\ensuremath{\Omega}$-dependent threshold. A transition stationary state chaotic evolution is predicted upon increasing nonlinearity. shortest typical time scale intensity fluctuations order $1/{\ensuremath{\Omega}}_{\mathrm{max}}.$