Photoinduced light scattering in crystals with a nonlocal response

Temporal evolution of fanning in photorefractive materials

“…3 Similar expansions have been used previously for fanning by Kukhtarev' 4 and by Obukhovskii and Stoyanov. 2 Limitations inherent in this technique are discussed by Crosignani et al' 5 To isolate the physics of beam fanning alone, we neglect interactions between orthogonal components (anisotropic scattering), assume a monochromatic incident beam and stationary scattering centers, and include only two spatial dimensions.…”

“…The electric field E(x, z, t) of the optical beam propagating in the z direction may be written in the form (2) where A(x, z, t) is the slowly varying part of the field, x is the transverse coordinate, k = Wnb/C is the optical wave number, nb is the background refractive index in the crystal, e is the angular separation of the plane waves, and am(z, t) are the expansion coefficients. The amplitude A obeys the paraxial wave equation…”

Photoelectric fields in lithium niobate crystals

“…1 When laser radiation is transmitted through a photorefractive crystal, photoinduced light scattering (PILS) occurs at the static and dynamic (fluctuating) defects induced by the laser radiation, with variation of the refractive index. 7 The value of the electrooptic effect in this case determines the divergence angle of the PILS distribution, which in lithium niobate lies predominantly along the polar axis of the crystal. The value and rate of the divergence angle of the PILS distribution determine the sensitivity and response rate of the photorefractive holographic recording of information and of electrooptic modulators and shutters.…”

Beam fanning used to study thermal disorder and decay of polar structures in the ferroelectric relaxor Sr 0.61 Ba 0.39 Nb 2 O 6

“…The signs "−" or "+" indicate that scattering is either depleted or amplified. The exact equations for Γ for beam fanning in SBN can be found in [14]. The preexponential factor I ±θs so in eq.…”