Optical and electrooptical materials

Levy D., Esquivias L. Sol-gel processing of optical and electrooptical materials. Adv. Mater. 1995 7 120-129... 

Nonlinear optical and electrooptic ceramics. Electronic properties and material stmcture. 

Approximately ten years ago, it was first reported by Haertling and Land (jj that optical transparency was achieved in a ferroelectric ceramic material. This material was, in reality, not just one composition but consisted of a series of compositions in the lanthanum modified lead zirconate-lead titanate (PLZT) solid solution region. The multiplicity of compositions, each with different mechanical, electrical and electrooptic properties has led to a decade of study in defining the chemical and structural nature of these materials in understanding the phenomena underlying their optical and electrooptic properties and in evaluating the practicality of the large number of possible applications (2-12),... 

CERAMICS - ELECTRONIC PROPERTIES AND MATERIAL STRUCTURE] (Vol 5) [CERAMICS - NONLINEAR OPTICAL AND ELECTROOPTIC CERAMICS] (Vol 5)... 

Although the structure/property relationships have become more evident for alkyl substituted polythiophenes, the synthesis and characterization of new heterofunctionalized polythiophenes continues to be an active research area because there are a number of potential applications for new materials. There is still much to be learned about the structure/property relationships in these functionalized polymers. The effects of these side chains on the stability, solubility and self-assembly of these polymers as well as their effects on the electronic, optical and electrooptical properties are largely unknown. An improved understanding of the structure/property relationships will, in turn, drive the rational synthesis of new, functionalized polymers with optimized properties. 

In an electrooptic material the phase retardation angle is controlled by altering birefringence, which is in turn controlled by the potential of an apphed electric field. An electrooptic device thus acts as a variable phase optical retardation plate, and can be used to modulate the wavelength or intensity of an incident beam. 

We recognize that there are applications in two- and three-dimensional waveguides (12,13) which do not have the same criteria of phase-matching as in simple crystals or that one may just as well be interested in screening these materials for the related electrooptic performance by the simple SHG powder method. (It has been shown for several organic materials that although the electro-optic and SHG x tensors are in principle unequal, due to dispersion and due to the possible contribution of atomic and molecular distortions... 

LiNbOj is a widely used ferroelectric crystal with various applications in the nonlinear optics and integrated optics (10). Another attractive material for 10 devices is LiTaOs. Its electrooptic (EO) and nonlinear (NL) coefficients are comparable to those of LiNbOj, and its photorefractive damage threshold is more than an order of magnitude higher than that of LiNbOj in the visible range. 

Although only rarely luminescent in ambient fluid solutions, square-planar transition metal bis(dithiolene) complexes do display significant and varied photochemical reactivity. Much of the photoreactivity described above for dianionic bis(dithiolene) complexes involves excited-state oxidation and often leads to radical formation. In addition, the excited states of these complexes are receiving attention for their potential as materials for optical (15), nonlinear optical (10-13), and electrooptical (16) devices. The relevance of this work to those applications is addressed in other parts of chapter 8 in this volume (87b). 

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