Electro-optic materials

The effective use of coherent optical radiation in communications requires low power, wide bandwidth modulators. The most promising modulator materials are those with refractive indices sensitive to electric field. Certain of these materials are also useful in nonlinear optical applications such as optical frequency doublers and optical parametric oscillators. The search for efficient modulator, frequency doubler, and parametric oscillator materials has led to the preparation of a large number of single crystals in the class of oxygen octahedra ferroelectrics. This class includes, for example, lithium niobate, barium sordium niobate and barium titanate. Crystal growth and optical studies have led to nearly optimum electro-optical and nonlinear optical materials within this class. The growth and property control methods that have been used are closely related in many instances to those used in the preparation of single crystal semiconductors. While materials with optimum properties have been found, the requirement for high optical quality crystals that do not optically damage when irradiated with a laser have led to additional material requirements that can be met about which much remains to be understood.