Direct observation of plasmonic index ellipsoids on a deep-subwavelength metallic grating

Abstract

We constructed a metallic grating on a deep-subwavelength scale and tested its plasmonic features in visible frequencies. The deep-subwavelength metallic grating effectively acts as an anisotropic homogeneous uniaxial form-birefringent metal, exhibiting different optical responses for polarizations along different optical axes. Therefore, this form-birefringent metal supports anisotropic surface plasmon polaritons that are characterized by directly imaging the generated plasmonic index ellipsoids in reciprocal space. The observed plasmonic index ellipsoids also show a rainbow effect, where different colors are dispersively distributed in reciprocal space.

Numerical study of achiral phase-change metamaterials for ultrafast tuning of giant circular conversion dichroism

“…In all natural chiral molecules though, chiral responses tend to be very weak and detectable only if strong phase differences between RCP and LCP waves accumulate over a long optical path 2 . To solve this problem, periodically plasmonic nanostructures known as chiral metamaterial (MM) and achiral MM have been recently proposed to obtain large chiral effects like optical activity 4 , asymmetric transmission 10 and polarization conversion 11 12 13 14 15 . Particularly, chiral MM has two different mirror forms called enantiomers and non-chiral MM only breaks mirror symmetry under oblique incidence.…”