ABSTRACT
This chapter introduces the basic principles of nonlinear optical effects in organic materials. Various types of nonlinear optical processes are included, together with an overview of most important applications. The origins of optical and nonlinear optical response in solid materials are discussed, and key differences between inorganic and organic materials are described. Basic molecular structures of various types of organic materials for second-order nonlinear optics and models to describe their response are introduced. A separate discussion is devoted to organic nonlinear optical single crystals with best stability characteristics among organic nonlinear optical materials.
