Laser-Induced Chirality of Plasmonic Nanoparticles Embedded in Porous Matrix

Area of Science:

• Plasmonics
• Nanophotonics
• Chirality

Background:

• Chiral plasmonic nanostructures are vital for nanophotonics, optoelectronics, biosensing, chemistry, and pharmacy.
• Achiral gold nanoparticles typically form racemic mixtures within nanoporous matrices.

Purpose of the Study:

• To develop a novel method for inducing strong chirality in achiral gold nanoparticle ensembles.
• To investigate the creation of chiral plasmonic nanostructures using circularly-polarized laser light.

Main Methods:

• Irradiation of gold nanoparticles embedded in a nanoporous silicate matrix with circularly-polarized picosecond Nd:YAG laser light.
• Utilizing a modified spectral hole burning technique to selectively modify chiral nanoparticles.

Main Results:

• Achiral gold nanoparticles were transformed into chiral plasmonic nanostructures with strong circular dichroism (up to 100 mdeg).
• Both 2D and 3D nanostructures contributed significantly and equally to the observed circular dichroism signals.
• The resulting circular dichroism was independent of the light propagation direction.

Conclusions:

• A novel method successfully induced strong chirality in achiral gold nanoparticles.
• The findings pave the way for developing passive optical modulators and enhanced chiral sensing/catalysis platforms.
• The equal contribution of 2D and 3D structures to circular dichroism offers new insights into chiral nanophotonics.