Mid-infrared pulsed lasers operating around the 3?μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack of a nonlinear optical modulator operating in the mid-infrared regime remains a significant challenge. Here, we report the third-order nonlinear optical response of gold nanorods (GNRs) ranging from 800?nm to the mid-infrared regime (2810?nm) enabled by their size and overlapping be