Three-Dimensional Visualization of Chiral Nano-Optical Field around Gold Nanoplates via Scanning Near-Field Optical...

Area of Science:

• Plasmonics
• Nanophotonics
• Chiroptical Physics

Background:

• Chiral optical fields are essential for understanding light-matter interactions.
• Gold nanostructures exhibit unique plasmonic properties that can be harnessed for optical applications.
• Near-field optical microscopy provides high-resolution imaging of optical fields at the nanoscale.

Purpose of the Study:

• To investigate the three-dimensional chiral optical field near a gold nanoplate.
• To understand the spatial distribution and polarization dependence of the chiral optical field.
• To explore the modal contributions to the chiral optical field and its spatial extension.

Main Methods:

• Aperture-type scanning near-field optical microscopy (SNOM) was employed.
• Near-field imaging was used to map the chiral optical field.
• Modal analysis was performed to determine the contribution of different plasmon modes.

Main Results:

• The chiral optical field exhibits a unique spatial distribution dependent on incident polarization.
• Plasmon modes with E symmetry significantly contribute to the chiral field, while A1 symmetry modes contribute minimally.
• The 3D visualization shows the chiral field extends further than the plasmonic optical field due to unique electric and magnetic field distributions.

Conclusions:

• The study provides detailed insights into plasmon-enhanced chiral fields.
• The findings establish a fundamental basis for developing highly sensitive plasmon-based chiral molecule sensors.
• Understanding the spatial characteristics of chiral optical fields is key for advanced optical sensing applications.