Stochastic models for light-scattering noise in nonlinear optical Kerr media

Measurements of light-scattering noise accompanying two-wave mixing in a Kerr medium

“…Recent studies based on the fluctuation-dissipation theorem have shown that the optical Kerr coefficient is fundamentally associated with thermal fluctuations in the linear dielectric constant of the medium. These fluctuations reduce the fidelity of an optical signal by mixing in scattered light from the pump-laser field as noise [5,6]. In this Rapid Communication we report measurements of noise during two-wave mixing in a Kerr medium and demonstrate excellent agreement with theoretical predictions for thermal light-scattering noise [7].…”

“…Inserting Eq. (1) into the wave equation, making the slowly varying amplitude and phase approximation, and equating the in-phase and out-ofphase terms gives a set of four coupled equations describing the evolution of the two amplitudes and two phases, which may be integrated using the stochastic noise model [6,7]. In the absence of pump depletion and background loss, an analytic solution to these equations may be obtained, which is sufFicient for comparison with the present measurements.…”

“…The right-hand side of Eq. (5b) may be evaluated in terms of the nonlinear dielectric constant, or Kerr coefficient, e2 using [5,6] …”

Light-Scattering Fluctuations and Noise in Nonlinear Optical Processing

“…Dielectric fluctuations that originate from fluctuations in the space-charge field follow immediately from Equation 5 through the Pockels effect 8e fi e(2) osc (6) where e ( 2 ) is related to the electro-optic tensor, r, and the refractive index of the medium, nR. The standard relations An = -(l/2)nR 3 rE, for the index change, and Ae = 2nRAn yield e(2) = -nR 4 r (…”

“…In the following sections, the theory of light-scattering noise in Kerr media is extended using the fluctuationdissipation theorem (Ref. 6). This generalization of the static susceptibility relation is required for applications to time-dependent processes and noalinear optical media exhibiting power dissipation.…”