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Investigation on Some Fast Optical/Opto-Electronic Switching Systems for Implementing Different Modulation Schemes
Published in Arpan Deyasi, Pampa Debnath, Asit K. Datta, Siddhartha Bhattacharyya, Photonics, Plasmonics and Information Optics, 2021
Minakshi Mandal, Suranjan Lakshan, Debashri Saha, Agnijita Chatterjee, Sourangshu Mukhopadhyay
The electro-optic effect is the variation of the refractive index of a medium, caused by an externally applied electric field. When a polarized laser light beam passes through an electro-optic Pockels material, a change in refractive index occurs with the application of an electric field to the material, and this change in refractive index is linearly proportional to the applied field strength. This effect is called the electro-optic pockels effect.
An Introduction to Photorefractive Polymers
Published in Hari Singh Nalwa, Seizo Miyata, Nonlinear Optics of Organic Molecules and Polymers, 2020
B. Kippelen, K. Meerholz, N. Peyghambarian
The analysis presented above stands for a purely linear electro-optic material. Other effects can also contribute to the refractive index change induced by the applied field. Piezoelectricity, for instance, leads to a thickness change of the sample and is, therefore, also inducing a phase change in the Mach- Zehnder apparatus. Since piezoelectricity is an effect that is linear in the electric field, its contribution cannot be discriminated from the linear electro-optic effect. Moreover, higher order effects such as the quadratic electro-optic effect or Kerr effect can also contribute to the modulated signal at frequency ?, especially when a space-charge field introduced in the sample during the poling process leads to an internal DC field that is superimposed to the external AC field. Many other effects such as birefringence orientational effects,60 higher order effects including electronic and orientational third-order effects, electrode attraction, electrostriction, or heating effects,73 can possibly contribute to the overall refractive index changes. Higher order effects can lead to a signal modulated at frequency 2? which can yield valuable information on the third-order nonlinear optical properties of the polymer.101 The relative strength of each of these possible contributions has not yet been clearly established in photorefractive polymers and more work needs to be done.
Electro-Optic, Acousto-Optic, and Liquid Crystals
Published in Solomon Musikant, Optical Materials, 2020
The electro-optic effect (Pockels effect) is the change in the indices of refraction of the ordinary and the extraordinary rays that is caused by and is proportional to an applied electric field. The electro-optic effect was discovered by Roentgen and extensively investigated by F. Pockels around the turn of the nineteenth century. This effect occurs in certain crystals known as electrooptic crystals.
Accurate second Kerr virial coefficient of rare gases from the state-of-the-art ab initio potentials and (hyper)polarizabilities
Published in Molecular Physics, 2020
The Kerr effect, discovered by John Kerr in 1878 [1], describes the refractive-index change of a material when an electric field is applied. The Kerr electro-optic effect has a fast response to the change of an external electric field and is the basis for electronic controlled optical switches. The Kerr optical effect means that the change of refractive index is proportional to the intensity of light. Its most well-known application nowadays is Kerr-lens modelocking. For an ideal gas, Buckingham et al. [2,3] found that the Kerr constant Km is linearly proportional to the gas density ρ: where the coefficient AK (also called the first Kerr virial coefficient) depends on the atomic second hyperpolarizability γ0. With increasing pressures or densities, the deviations from Eq. (1) can be observed and the terms quadratic, cubic and higher in density contribute to Km(ρ): where BK(T) and CK(T) are the second and third Kerr virial coefficients, respectively and T is the temperature.
Uniform asymptotics of solutions of the wave operator with meromorphic coefficients
Published in Applicable Analysis, 2023
Maria V. Korovina, Hovik A. Matevossian, Ilya N. Smirnov
In this paper the problem of wave propagation in the medium whose velocity characteristics change under an external impact in three-dimensional case is considered. We study the problem of constructing the asymptotics of solutions for a wave equation with a variable coefficient that depends on time at the Laplacian and is a meromorphic function in a neighborhood of infinity. For the first time, a physical interpretation of such a problem was considered in [1], in which the phenomenon of light self-focusing was studied. This phenomenon is one of the effects of self-action of light and manifests itself in the concentration of the light-beam energy in the nonlinear medium with a refractive index that increases with increasing light intensity. It was also shown there that the ionizing, thermal, and separating effect of the beam of intensive radiation on the medium can be so strong that it leads to a drastic difference between the medium properties in the beam and outside it, which results in the waveguide propagation of the beam and eliminates its geometrical and diffraction divergence; this interesting phenomenon can be called the self-focusing of the electromagnetic beam. Later, the foundations of a mathematically rigorous theoretical description of this phenomenon were laid in [2]. However, still in 1875, J. Kerr discovered the Kerr effect, or the quadratic electro-optic effect – the phenomenon of a change in the value of refractive index of an optical material caused by an applied electric field and being proportional to the square of the electric field strength. The Kerr effect can be observed in all media, however, for some liquids, it is more pronounced than for other substances.
Ferroelectric, Piezoelectric Mechanism and Applications
Published in Journal of Asian Ceramic Societies, 2022
Arun Singh, Shagun Monga, Neeraj Sharma, K Sreenivas, Ram S. Katiyar
The electro-optic effect can be employed in optical modulators and display systems. A thin film, electro-optic light modulators is shown in Figure 13 (c) [33]. The light is coupled with the film by using a prism coupling (not shown in the figure). The small separation between electrodes across the optical wave guide enables the application of large electric fields at relatively low voltages. The change in polarization depends on the applied field and the length of the waveguide. An applied ac signal can produce intensity variations in a polarized light beam when seen through an analyzer.