Ultrahigh field enhancements from nanostructured metal thin films (Conference Presentation)

Abstract

Enhancing the optical fields near metal nanostructures is of high importance for sensing, energy harvesting and improving the efficiency of optoelectronic devices. Surface enhanced spectroscopies such as Raman scattering (SERS), fluorescence (SEF) and infrared absorption (SEIRA) are enhanced significantly thus allowing lower detection limit and suprresolved imaging. Solar energy harvesting can be improved by designing structures that enhance the local optical field over wide spectral and angular ranges covering the whole solar spectrum. Detectors for the short wave and mid-IR ranges with higher efficiencies started to appear following an optimum designs incorporating plasmonic nanostructures. During the last few years we have been investigating several plasmonic nanostructured thin films for improved biosensors and lately for energy harvesting devices using variety of configurations: standard Kretchmann-Raether configuration, grating coupling, free space excitation of localized plasmons (LSPs) from nanosculptured thin films, and lately excitation of LSPs via extended surface plasmons (ESPs). The later configuration was shown both theoretically and experimentally (using SEF and SERS) to reveal extraordinary enhancement when the matching conditions between the ESP and the LSP are met. Several configurations for improved SPR biosensors and ultrahigh enhancement of local optical fields will be presented with the potential applications in sensing, solar energy harvesting and optoelectronic devices. Acknowledgments: This research was conducted partially by NTU-HUJ-BGU Nanomaterials for Energy and Water Management Programme under the Campus for Research Excellence and Technological Enterprise (CREATE), that is supported by the National Research Foundation, Prime Minister’s Office, Singapore.