Fabrication and Applications of Long-Range Ordered Au Nanodisk Arrays

Large-scale nanostructure arrays with spatial coherence are useful for many applications. Conventional nanofabrication techniques such as electron beam lithography and focused ion beam lithography are expensive and time-consuming. In this paper, long-range ordered Au nanodisk arrays were fabricated on glass substrates using nanosphere lithography (NSL) combined with reactive ion etching (RIE) techniques. The morphology and size distribution of the Au nanodisks were examined with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensitivity of the localized surface plasmon resonance (LSPR) of the Au nanodisk arrays to change in the surroundings’ refractive index was evaluated by integrating the Au nanodisk arrays into microfluidic channels. The measured sensitivity was supported by discrete dipole approximation (DDA) calculations. Further, we designed and fabricated an all-optical plasmonic switch based on the Au nanodisk arrays and photoresponsive liquid crystals (LCs). The high-quality optical properties and high-degree spatial uniformity of the nanodisk arrays, together with simple, low-cost fabrication and easy integration with microfluidic system, suggest tremendous potential in using these nanostructures in many other applications, including biosensing and imaging, surface-enhanced Raman spectroscopy (SERS), and plasmonic tweezers.