Second-harmonic generation in gold crescent- and comma-like nanostructures.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Anisotropic metal nanostructures possess unique optical properties.
• Nonlinear-optical (NLO) phenomena are crucial for advanced optical applications.
• Understanding NLO responses in nanostructures is key to developing new optical effects.

Purpose of the Study:

• To experimentally investigate the nonlinear-optical response of anisotropic gold nanostructures.
• To explore the influence of particle shape and susceptibility phase on NLO anisotropy.
• To quantify circular dichroism in second-harmonic generation (SHG).

Main Methods:

• Fabrication of planar arrays of comma-like and crescent-like gold nanostructures using colloidal lithography.
• Experimental characterization of the nonlinear-optical response.
• Analysis of spectrally sensitive second-order susceptibility components.

Main Results:

• Demonstrated anisotropy in the nonlinear-optical response of gold nanostructures.
• Identified particle shape and relative phase of susceptibility components as key factors defining NLO anisotropy.
• Observed high circular dichroism (up to 70%) in the SHG response of comma-like nanostructures.

Conclusions:

• The shape and spectral phase of anisotropic nanostructures critically determine their nonlinear-optical response.
• Comma-like gold nanostructures exhibit significant circular dichroism in SHG.
• These findings contribute to the development of novel optical effects and devices based on nanophotonics.