Organic second-order nonlinear optical crystals: materials for terahertz

In recent years, the application of terahertz technology has gained substantial recognition across various domains. Nonlinear optical crystals have garnered emerged as a focal point of attention due to their pivotal role in advancing this technology. Within the realm of these crystals, organic second-order nonlinear optical materials stand out for their remarkable attributes. Their large nonlinear coefficient, elevated electro-optical coefficient, and low dielectric constant position them as exceptional materials for terahertz radiation sources. This article delves into a comprehensive exploration of two distinct categories of crystals: ionic and molecular. It provides an insightful overview of the structural design strategies employed in these crystals. Furthermore, this paper conducts a thorough analysis of the shared and different properties between these diverse crystal types, including optical, thermal, mechanical and nonlinear aspects. This in-depth exploration paves the way for a better understanding of the potential applications of these crystals in the ever-expanding realm of terahertz technology.