In the fast evolving field of nanoscience and nanotechnology,where size and shape are crucial in deciding the optoelectronic properties of nanomaterials,the understanding of size and shape dependent behavior is of direct relevance to device applications.Present study reports the synthesis of Au nanorods with well controlled aspect ratios,and the influence of the aspect ratio on the surface enhanced Raman scattering(SERS) activity using crystal violet(CV) as the probe molecule.The influence of pH and the concentrations of reducing agent and Ag ions in controlling the aspect ratio of gold nanorods are also investigated.The structural and optical properties of the synthesized samples have been characterized by transmission electron microscopy(TEM) and UV-visible absorption spectroscopy.The nonlinear optical(NLO) transmission of the Au nanorods investigated using the open aperture Z-scan technique revealed the absorption saturation followed by an optical limiting behavior,which may find potential applications in optoelectronic nanodevices. In the fast evolving field of nanoscience and nanotechnology, where size and shape are crucial in deciding the optoelectronic properties of nanomaterials, the understanding of size and shape dependent behavior is of direct relevance to device applications. Present study reports the synthesis of Au nanorods with well controlled aspect ratios, and the influence of the aspect ratio on the surface enhanced Raman scattering (SERS) activity using crystal violet (CV) as the probe molecule. The influence of pH and the concentrations of reducing agent and Ag ions in controlling the aspect ratio of gold nanorods are also investigated in the structural and optical properties of the developed samples have been characterized by transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. the nonlinear optical (NLO) transmission of the Au nanorods investigated using the open aperture Z -scan technique revealed the absorption saturation followed by an optical limiting behavior, which may find po tential applications in optoelectronic nanodevices.