Open AccessLarge-area electromagnetic enhancement by a resonant excitation of surface waves on a metallic surface with periodic subwavelength patterns
Author(s) -
Xin Zhang,
Haitao Liu,
Ying Zhong
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.024139
Subject(s) - surface plasmon polariton , optics , excitation , surface wave , surface plasmon , electromagnetic radiation , materials science , polariton , electromagnetic field , electric field , resonance (particle physics) , near and far field , nanophotonics , surface plasmon resonance , plasmon , optoelectronics , physics , nanotechnology , atomic physics , nanoparticle , quantum mechanics
We theoretically investigate the electromagnetic enhancement on a metallic surface patterned with periodic subwavelength structures. Fully-vectorial calculations show a large-area electromagnetic enhancement (LAEE) on the surface, which strongly contrasts with the previously reported "hot spots" that occur in specific tiny regions and which relieves the rigorous requirement of the nano-scale location of sample molecules. The LAEE allows for designing more practicable substrates for many enhanced-spectra applications. By building up microscopic models, the LAEE is shown due to a resonant excitation of surface waves that include both the surface plasmon polariton (SPP) and a quasi-cylindrical wave (QCW). The surface waves propagate on the substrate over a long distance and thus greatly enlarge the area of electromagnetic enhancement compared to the nano-sized hot spots caused by localized modes. Gain medium is introduced to further strengthen the large-area surface-wave resonance, with which an enhancement factor (EF) of electric-field intensity up to a few thousands is achieved.