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Paradigm Shift of On-Chip Interconnects from Electrical to Optical
Published in Thomas Noulis, Noise Coupling in System-on-Chip, 2018
Swati Joshi, Amit Kumar, Brajesh Kumar Kaushik
Modulators are essential components in photonics circuits. They control the characteristics of light through the circuits according to an external modulating signal. There are stringent requirements for optical modulators to meet complex future demands, such as high speed, low energy per bit, compact design, low loss, large optical bandwidth, modulation depth, low-temperature sensitivity, CMOS compatible process flow, and low drive voltage. The thermo-optic effect, electro-optic effect, and microelectromechanical systems (MEMS) are some of the current optical modulation schemes. In an electro-optic modulator, the electro-optic effect is used to modulate a beam of light. The modulation can be in terms of change of intensity, phase, or polarization of the output beam. MEMS and thermal effects find less application in current devices due to their slow speed. An optical modulation scheme is shown in Figure 14.27.
Advanced optics
Published in John P. Dakin, Robert G. W. Brown, Handbook of Optoelectronics, 2017
Planar waveguides find interesting application in integrated optics. In this, waves are guided by planar channels and are processed in a variety of ways. An example is shown in Figure 7.33. This is an electro-optic modulator and it utilizes electro-optic effect (see Section 7.7.7), whereby the application of an electric field to a medium alters its refractive index. However, the electric field is acting on a waveguide that, in this case, is a channel (such as we have just been considering) surrounded by “outer slabs” called here a “substrate.” The electric field is imposed by means of the two substrate electrodes, and the interaction path is under close control, as a result of the waveguiding. The material of which both the substrate and the waveguide are made should, in this case, clearly be an electro-optic material, such as lithium tantalate (LiTaO3) whose refractive index depends upon the applied electric field. The central waveguiding channel may be constructed by diffusing ions into it (under careful control); an example of a suitable ion is niobium (Nb), which will thus increase the refractive index of the “diffused” region and allow TIR to occur at its boundaries with the “raw” LiTaO3. Many other functions are possible using suitable materials, geometries, and field influences. It is possible to fabricate couplers, amplifiers, polarizers, filters, etc., all within a planar “integrated” geometry.
Computational Methods for Dynamic Electro‐Optic Properties of Macromolecules and Nanoparticles in Solution
Published in Stoyl P. Stoylov, Maria V. Stoimenova, Molecular and Colloidal Electro-Optics, 2016
J. García de la Torre, F.G. Díaz Baños, H.E. Pérez Sánchez
Electro‐optics consider the optical (or spectroscopic) properties induced in a material by the application of an electric field. A commonly observed property is the birefringence, Δn, defined as the difference between the refractive index of the material in the direction of the applied field and that in a perpendicular direction. The material system is, in our case, a dilute solution, and Δn designates the contribution of the solute, obtained by discounting the contribution of the solvent (if appreciable) from that of the solution. Birefringence, and in general the electro‐optic properties, are caused by the orientational effect of the field on the polar or polarizable (and, in the case of birefringence, optically anisotropic) solute molecules, whose orientation, which is uniformly random in the absence of the fields, becomes still random, although not uniform but biased by the external agent. Let α denote the optical polarizability of a molecule, with a given orientation, referred to a laboratory‐fixed system of coordinates such that the electric field is applied along the vertical axis, z. Following the classical monograph of Frederick and Houssier [1], we write the birefringence as Δn=Knv〈Δα〉
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.
Optical response properties of a hybrid electro-optomechanical system interacting with a qubit
Published in Journal of Modern Optics, 2022
Tarun Kumar, Surabhi Yadav, Aranya B. Bhattacherjee
Electro-optic modulators (EOMs) used in optical communication systems have the ability to modulate an optical field using an electric field. One of the major challenge to implement such an EOM is low power consumption [78]. EOMs based on Pockels effect and Kerr effect require large components together with high driving voltage [79,80], leading to high energy dissipation [81]. EOMs based on the electro-absorption effects are also not fully successful due to the weakness of the electro-optic absorption effect [82]. These limitations led to a novel proposal of a hybrid EOM system composed of a three-level medium confined inside a tunable cavity coupled to an electro-mechanical system [83].
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.