The role of chiral local field enhancements below the resolution limit of Second Harmonic Generation microscopy

Abstract

While it has been demonstrated that, above its resolution limit,
\nSecond Harmonic Generation (SHG) microscopy can map chiral local field
\nenhancements, below that limit, structural defects were found to play a
\nmajor role. Here we show that, even below the resolution limit, the
\ncontributions from chiral local field enhancements to the SHG signal can
\ndominate over those by structural defects. We report highly homogeneous
\nSHG micrographs of star-shaped gold nanostructures, where the SHG
\ncircular dichroism effect is clearly visible from virtually every single
\nnanostructure. Most likely, size and geometry determine the dominant
\ncontributions to the SHG signal in nanostructured systems.