Index electric field dependence

The nonlinear index of refraction is related to the applied electric field, E, through the electric-field-dependent susceptibility, Xen of a material. 

Photorefractive materials have attracted considerable interest because of their potential applications in electro-optic devices, e.g., for holograms, optical computing, or as storage media for erasable read-write optical memories. As their name implies, photorefractive materials are photosensitive and have an electric field-dependent refractive index. 

Non-stationary self-effects of the light beam depend on the pulse duration with respect to the time Tr of nonlinear response of the medium. When the response is instantaneous, the refractive index at the time t is defined by the value of electrical field at the same moment. If the time of a nonlinear response is finite, the nonlinear part of the refractive index satisfies the... 

Electrooptic materials. The dependence of refractive index on the electric field or the lattice polarization is referred to as the electrooptic effect ... 

Physical properties of liquid crystals are generally anisotropic (see, for example, du Jeu, 1980). The anisotropic physical properties that are relevant to display devices are refractive index, dielectric permittivity and orientational elasticity (Raynes, 1983). A nematic LC has two principal refractive indices, Un and measured parallel and perpendicular to the nematic director respectively. The birefringence An = ny — rij is positive, typically around 0.25. The anisotropy in the dielectric permittivity which is given by As = II — Sj is the driving force for most electrooptic effects in LCs. The electric contribution to the free energy contains a term that depends on the angle between the director n and the electric field E and is given by... 

Thus, the linear polarizability a (responsible for the value of the refractive index n) can be treated as an electric field amplitude-dependent quantity, i.e., aeff = a + (3-yEo)/4. Remembering that the light intensity is proportional to the square of the field amplitude, this means that the third-order nonlinearity leads to the linear dependence of the refractive index on the light intensity and that, for example, the phase of the propagating beam is modified at high light intensities due to this dependence. 

Separation of Electronic and Nuclear Motions. The polarizabilities of the ground state and the excited state can follow an electronic transition, and the same is true of the induced dipole moments in the solvent since these involve the motions of electrons only. However, the solvent dipoles cannot reorganize during such a transition and the electric field which acts on the solute remains unchanged. It is therefore necessary to separate the solvent polarity functions into an orientation polarization and an induction polarization. The total polarization depends on the static dielectric constant Z), the induction polarization depends on the square of the refractive index n2, and the orientation polarization depends on the difference between the relevant functions of D and of n2 this separation between electronic and nuclear motions will appear in the equations of solvation energies and solvatochromic shifts. 

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