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Electro-optic Ceramics and Devices
Published in Lionel M. Levinson, Electronic Ceramics, 2020
Electro-optic materials provide the medium by which electrical information can be transformed into optical information or by which optical functions can be performed upon command from an electrical signal. These materials are typically single crystals, such as KDP, LiNbO3, LiTaO3, and SBN, and they may even be liquid crystals, which have recently found widespread acceptance as light valves and displays because of their low-voltage operation (integrated circuit (IC) compatible) and their low power consumption. However, no single material as yet meets all the requirements of the many demanding applications, and there is a continual search for new materials to meet specific needs.
Comparison of Measurement Reliability of Nanosecond Rectangular Voltage Pulses by Kerr Effect and by High-Speed Voltage Probe
Published in Fusion Science and Technology, 2022
Nemanja Aranđelović, Dušan Nikezić, Dragan Brajović, Uzahir Ramadani
For the measurement of rectangular voltage pulses, it was found that the measurement with the electro-optical Kerr effect is somewhat superior to the measurement with a fast capacitive probe. However, the advantage of the electro-optical method is not enough to give it an absolute advantage over the classical measurement. The presented results were obtained under highly controlled laboratory conditions. In engineering practice, such conditions are difficult to achieve and are extremely uneconomical in terms of time spent and the price of the necessary equipment. With all this in mind, without a doubt, we would suggest that the EBG voltage pulse be measured with classical capacitive probes. Electro-optical methods may in the future enable the understanding of some hitherto unexplained phenomena. This primarily refers to the possibility of using miniature laser diodes and optical fibers that maintain the angle of polarization when propagating through the optical fiber. Of course, in the future we can expect the progress of fast capacitive probes, primarily by synthesizing new materials of electronic type of polarization. With this in mind, it is difficult to expect that in the future the voltage pulse of the EBG waveguide will be recorded using electro-optical methods.
Depolarization effect on the electro-optical properties of polymer-stabilized sphere phase liquid crystal
Published in Liquid Crystals, 2020
Pei-Yun Guo, Dong-Peng Sun, Ji-Liang Zhu
where k and r are the average elastic constant and radius of the 3-DTSs, respectively. μ1 represents a dimensionless factor, signify the depolarisation of the applied field, ξ indicates the average curvature radius with the applied electric field E. When an electric field (E) is applied, the liquid crystals in disclinations of PS-SPLC will be in response to external fields, birefringence is induced and the refractive index of the disclinations is described by the Kerr effect [21–23], which is valid only in the low electric field region. As the E increases, birefringence cannot increase indefinitely, i.e., it will gradually saturate. In order to accurately describe the electro-optical properties of the high electric field, we quote the extended Kerr effect. The refractive index of the disclinations can be written as follows [10]:
Fast switching beam steering based on ferroelectric liquid crystal phase shutter and polarisation grating
Published in Liquid Crystals, 2019
Qi Guo, Lin Xu, Jiatong Sun, Xiaoqian Yang, Hongwei Liu, Kexin Yan, Huijie Zhao, V. G. Chigrinov, H. S. Kwok
Rapid and precise steering of laser beams with no mechanical parts is an attractive task and in high demand for modern electro-optical systems [1–3] such as free space optics and laser communication. Among various technologies [4], liquid crystal beam steering device is most promising due to its high birefringence [5], and low power-consumption [6]. However, the current commercial technology is limited by complicated device operation [1,7]. The method based on sawtooth phase profile by either polymer dispersion or variable alignment suffers from low efficiency (<80%) for large steering angle (>5°) [8]. Recently, a new method, which is based on controlling the geometric phase by variable azimuthal angle of the liquid crystal directors to realise polarisation grating (PG), exhibits high efficiency (theoretical ~100%) steering of laser beam with discrete large angles [4,9,10]. Quasi-continuous steering angles with resolution of 2.6° was reported by cascading PGs with high efficiency remains [11]. Previous efforts were mainly focused on steering angle and efficiency optimisation, yet little attention was paid on steering speed for long wavelength applications. The major challenge for rapid steering is the relaxation of electrically controlled birefringence of nematic liquid crystal [12].