**3. NLO crystal of current interest**

Significant developments in new technologies are responsible for the development of new crystals of superior quality. The high-speed and significant amount of optical parallelism would ultimately lead to optoelectronics devices which were a wide range of optical functions will be implemented. The growth of photonic technology, however, depends mainly on the progress made in developing new optical material with improved performance. Crystals with the nonlinear optical response (NLO) are expected to play an important role in facilitating optoelectronic and photonic developments. In optical and electro-optical applications, several NLO crystals have been found out as potential candidates. With the development of many devices using solid-state laser sources, nonlinear optical crystals have received special revolution. For the manufacture of electro-optic modulators that converts an electrical signal into an optical signal and transmission on a fiber optic cable, NLO crystals are very important. Currently, such devices are made with inorganic NLO materials. In this view, further new other crystals should be developed. Recently researcher is showing their keen interest in the development of organic–inorganic salts which show good optoelectronics characteristics [5–12].
