Rainbow Trapping Nanostructures: Ultra-high Field Intensity Platform for SERS Sensing

Subwavelength rainbow trapping metamaterial nano-gratings provide a unique means for high sensitivity and multiplexed molecular detection through localized and propagating surface plasmon polaritons. Herein we report on the viability of width-graded, depth-graded and chirped plasmonic nano-gratings for high sensitivity multiwavelength light localization. In addition, we introduce two classes of metal-insulator-metal (MIM) width-graded, i.e. formed in a semiconductor (SMIMS) and entirely in a metal (MIM). We show feasibility of SMIMS and MIM width-graded nano-gratings as unique SERS platforms in detecting human phospholipid and propylene glycol sample molecules.