Electrooptic effect linear

Second Harmonic Generation and Linear Electrooptic Effect in Solids... 

Nonlinear second order optical properties such as second harmonic generation and the linear electrooptic effect arise from the first non-linear term in the constitutive relation for the polarization P(t) of a medium in an applied electric field E(t) = E cos ot. 

Non-linear second-order optical properties such as second harmonic generation (SHG) and the linear electrooptic effect are due to the non-linear susceptibility in the relation between the polarization and the applied electric field. SHG involves the... 

There is great interest in preparing materials which could facilitate the development of electrooptic devices. Such devices could permit broad band optical signal encoding so that telephone, data, television, and even higher frequency transmissions could simultaneously be sent down a single optical fiber. The nonlinear optical process which makes this possible is the linear electrooptic effect (EO). It is based on the first field nonlinearities (Z ) of the molecular dipole moment, / ,... 

For the linear electrooptic effect (EO), the two-level model only differs in dispersion, with the dispersion factor, F q (co), given by... 

Figure 6.7. Upper linUts of x values reported for second harmonic generation of poled polymers, crystals, and LB films compared with those of inorganic crystals. Also noted is x /or the linear electrooptic effect in LiNbOa-...

Some of the relevant applications of nonlinear optics are currently used in laser technology and fiber communications, such as optical frequency conversion, optical parametric oscillation and amplification, the linear electrooptic effect (Pockels... 

The linear electrooptic effect is tlie change in the index of refraction of a medium due to the presence of a dc or low-frequency electric field, in such a manner that the change in the index of refraction depends linearly in the strength of the low-frequency electric field. The linear electrooptic effect is tlie mechanism behind optical intensity modulators that are used in optical switching and fiber-optics communications, where the optical signal is modulated at high frequencies (out to 110 GHz) [7-9],... 

P. Rudquist, M. Buivydas, L. Komitov and S.T. LagerwaU, Linear electrooptic effect based on flexoelectricity in a cholesteric with sign change of dielectric anisotropy, J. Appl. Phys. 76(12), 7778-7783, (1994). 

Piezoelectrics. In the neutral-polar classes there are polar directions (not axes), which can be described by several vectors with their vector sum equal to zero. Such crystals do not possess spontaneous polarization and do not manifest polar properties (such as pyroelectric, photogalvanic or linear electrooptical effects) however, the polarization can be induced not only by an electric held but also by a pure mechanical stress. These crystals are called piezoelectrics. Examples are crystals of quartz or ZnS having cubic symmetry with four polar direction but no polar axis. Fig. 13.1b. Such crystals are used in technics as microphones, mechanical micro-motors and sensors, etc. 

The current (third) period, which may be called a colonization, involves wide electrooptical investigations of novel effects in ferroelectric liquid crystals [9, 10] and a study of exotic materials like polymeric and lyotropic mesophases, blue phases in cholesterics, well-ordered smectics, and so on. For conventional (nematic and cholesteric) phases the accent was shifted to the optimization of the material properties for electrooptical devices, though novel phenomena like the supertwist effect [11] and a gamma of linear electrooptical effects [12-14] have also been discovered. 

The first observation of natural optical anisotropy was made in 1669 by Bartolinius in calcite crystals, in which light travels at different velocities depending on the direction of propagation relative to the crystal structure. The electrooptic effect, electric-field-induced anisotropy, was first observed in glass in 1875 by J. Kerr. Kerr found a nonlinear dependence of refractive index on applied electric field. The term Kerr effect is used to describe the quadratic electrooptic effect observed in isotropic materials. The linear electrooptic effect was first observed in quartz crystals in 1883 by W. Rontgen and A. Kundt. Pockels broadened the analysis of this relationship in quartz and other crystals, which led to the term Pockels effect to describe linear behavior. In the 1960s several developments... 

In Fig. 62 this linear electrooptic effect is compared with the quadratic effect controlling the state of a twisted nematic device. 

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