Refractive index/indices field-dependent

Definition of Kerr Constants. In the presence of an external electric field E, the electric pemuttivity e( ) and magnetic permeability n(E) become functions of the field strength. As a consequence the refractive index n also depends on E ... 

When a crystal is subjected to an electric field E, two possible changes of the refractive index may occur depending on the symmetry of the crystal. 

If the optical pulse of a mode-locked laser is focused into an optical fiber, the intensity / becomes very high. The amplitude of the forced oscillations that the electrons in the fiber material perform under the influence of the optical field increases with the field amplitude and the refractive index becomes intensity dependent ... 

Attenuated total reflection, on which atr—ftir is based, occurs when the rarer medium is absorbing and is characterized by a complex refractive index (40). The absorbing characteristics of this medium allow coupling to the evanescent field such that this field is attenuated to an extent dependent on k. The critical angle in the case of attenuated total reflection loses its meaning, but internal reflection still occurs. Thus, if the internally reflected beam is monitored, its intensity will reflect the loss associated with the internal reflection process at the interface with an absorbing medium. 

In all cases the dielectric constant used is that of the pure solvent. Neglect of the solute is usually justified by its low concentration and the assumption that any necessary correction would be additive. In at least a few cases where the first two expressions have been employed the linearity of the results is to some extent dependent on how closely the refractive index of the solute meets the conditions n2 = 2.0 or 2.5 a situation not always recognized by the investigators. In one instance attempts have been made to clarify the role of solvent reaction field by examining solutes with different dipole moment orientations relative to the bonds involving coupled atoms. 

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