Crystal growth of nonlinear optical (NLO) active compounds is a rapidly growing field of research due to the numerous applications of these materials in the development of advanced optical devices. G. Ahila has contributed significantly to this field by conducting research on crystal growth and characterization of NLO active compounds such as hydroxyquinoline, furfurylamine, and 2-amino-6-methylpyridine. The crystal growth of NLO active compounds is a complex process that requires precise control over the growth conditions to obtain high-quality single crystals. G. Ahila has employed various growth techniques such as solvent evaporation, Bridgman method, Czochralski method, top-seeded solution growth, flux growth, and vapor transport method to obtain single crystals of these compounds with high quality and large size. The characterization of these single crystals is equally important to understand their optical properties and potential applications. G. Ahila has utilized various characterization techniques such as X-ray diffraction, powder diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, UV-Vis spectroscopy, optical microscopy, luminescence, exciton dynamics, and quantum efficiency to study the crystal structure, optical properties, and defects present in these crystals. The NLO active compounds synthesized by G. Ahila exhibit significant second harmonic generation (SHG) and third harmonic generation (THG) capabilities, which make them attractive for use in various optical devices such as laser systems, frequency converters, electro-optics, and optical modulators. The Kerr effect and birefringence exhibited by these compounds also make them useful for optical communication and data processing. The chromophores present in these organic and inorganic compounds play a crucial role in determining their NLO properties. By studying the crystallography and growth techniques of these compounds, G. Ahila has been able to manipulate the chromophores to tune their NLO properties. In conclusion, G. Ahila's research on crystal growth and characterization of NLO active compounds has contributed significantly to the development of advanced optical devices. The growth techniques and characterization methods employed by G. Ahila have resulted in the synthesis of high-quality single crystals