Ceramic Electro-Optic Devices

MAJOR PRODUCT APPLICATIONS composites, ceramics, refractories, abrasives, copy toner, electro-optic devices, polishing, electrical and engineering components, acid adsorption, catalyst, nanocomposites... 

Haertling, G.H. (1988) Electro-optic ceramics and devices. In Electronic Ceramics, L.M. Levinson (ed.), Marcel Dekker, New York, pp. 371-92. 

Some ceramics are transparent to light of specific frequencies. These optical ceramics are used as windows for infrared and ultraviolet sensors and in radar installations. However, optical ceramics are not as widely used as glass materials in applications in which visible light must be transmitted. An electro-optic ceramic such as lead lanthanum zirconate titanate is a material whose ability to transmit light is altered by an applied voltage. These electro-optic materials are used in color filters and protective goggles, as well as in memory-storage devices. 

Ceramic PLZT has a number of structures, depending upon composition, and can show both the Pockels (linear) electro-optic effect in the ferroelectric rhombohedral and tetragonal phases and the Kerr (quadratic) effect in the cubic paraelectric state. Because of the ceramic nature of the material, the non-cubic phases show no birefringence in the as-prepared state and must be poled to become useful electro-optically (Section 6.4.1). PMN-PT and PZN-PT are relaxor ferroelectrics. These have an isotropic structure in the absence of an electric field, but this is easily altered in an applied electric field to give a birefringent electro-optic material. All of these phases, with optimised compositions, have much higher electro-optic coefficients than LiNb03 and are actively studied for device application. 

A variety of devices have been designed by using transparent electro-optical ceramic materials, including variable optical attenuators (VOA), polarization controllers (PC), sinusoidal filters, dynamic gain flattening filters, tunable optical filters, and (2-switches, which have been described in detail in Ref. [129]. A brief description is given for some devices as follows. 

Song QW, Wang XM, Bussjager R, Osman J (1996) Electro-optic beam-steering device based on a lanthanum-modified lead zrrconate titanate ceramic wafer. Appl Opt 35 3155-3162... 

A material with high electric resistivity is categorized as an insulator material. When we pay attention to their dielectric polarization and apply the materials to the electronics circuits, we usually call them dielectrics . Dielectric ceramics are essential electrical materials for today s advanced electronics devices. Production quantity of the dielectric ceramic is the largest among the other electronics ceramics such as magnetic, semiconductors, insulators, resistors and piezoelectric, and electro-optic materials. Main applications are for ceramic capacitors and microwave resonators. The dielectric ceramics is classified into two groups based on their dielectric properties. 

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