Coherent multiple scattering of light in ( 2+1 ) dimensions

Abstract

We formulate a multiple scattering theory of light in media spatially disordered along two directions and homogeneous along the third one, without making any paraxial approximation on the wave equation and fully treating the vector character of light. With this formalism, we calculate the distribution of transverse momenta of a beam as it evolves along the optical axis, and unveil a phenomenon not captured by the paraxial equation: a cross-over from a scalar to a vector regime, visible in the coherent backscattering peak as polarization gets randomized.

Spin Hall Effect of Light in a Random Medium

“…To find them, we compare the intensity per unit surface of the coherent mode, I ≃ δ 2 /(πw 2 0 /2) exp(−z/z s ) with I d , the diffusive signal around. The latter was computed in [31] in the geometry of transverse disorder:…”

“…, where z p = 8z s /5 k4 0 and the diffusion coefficient D = k2 0 z s /2 [31]. The constraint I > I d then reads:…”

“…z + i0 + ) and the self-energy tensor is evaluated at the level of the Born approximation: [31]. To make the calculation concrete, we model the incident light by a collimated Gaussian beam E(r ⊥ , z = 0) = 2/( √ πw 0 ) exp(−2r 2 ⊥ /w 2 0 + ik 0 · r ⊥ )ε(z = 0) with unit polarization vector ε(z = 0) = (e x ′ + e iφ e y )/ √ 2 and waist w 0 such that w 0 k 0 ≫ 1.…”

“…at small angle of incidence θ ≃ k 0 /k ≡ k0 , with σ = sin φ the beam helicity, σ = +1 (−1) for left(right)-handed circular polarization [30]. The shift continuously increases as the beam propagates deeper in the random medium, until it saturates at ∼ 1/k 0 beyond a characteristic time z SH ≡ z s / k2 0 , where z s is the scattering mean free time [31]. The SHE vanishes for linearly polarized light, σ = 0.…”

Spin-orbit-coupled fluids of light in bulk nonlinear media

“…It is known that -in contrast to atomic gases -light propagating in inhomogeneous media is naturally subject to an intrinsic spin-orbit interaction, which is predicted by Maxwell theory [37,38]. Such a mechanism has been observed in a number of optical configurations involving light transmitted or reflected at dielectric interfaces [39], plasmonic slits [40], nonparaxial beams [41], or light propagating in random media [42,43]. In the context of fluids of light, signatures of an analogue spin Hall effect were reported in microcavity exciton-polaritons [44].…”