Giant colloidal silver crystals for low-loss linear and nonlinear plasmonics

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Ultrasmooth, macroscopic silver (Ag) crystals are crucial for understanding silver's plasmonic potential and developing integrated plasmonic devices.
• Current limitations in silver crystal quality hinder the full characterization and application of silver in plasmonics.

Purpose of the Study:

• To demonstrate the growth of large, single-crystal silver plates for plasmonic applications.
• To investigate the propagation lengths of surface plasmon polaritons (SPPs) in these novel silver crystals.
• To enable the fabrication of reproducible plasmonic nanostructures for enhanced nonlinear optical processes.

Main Methods:

• Growth of millimetre-sized, single-crystal silver plates.
• Measurement of surface plasmon polariton propagation lengths using the fabricated silver crystals.
• Fabrication of double-resonant nanogroove arrays via focused ion beam milling.
• Characterization of second-harmonic generation (SHG) from the nanostructures.

Main Results:

• Achieved millimetre-sized single-crystal silver plates with ultrasmooth surfaces.
• Measured surface plasmon polariton propagation lengths exceeding 100 μm in the red wavelength region, surpassing predictions from established data.
• Fabricated highly reproducible plasmonic nanostructures, enabling uniform and spectrally tunable second-harmonic generation over large areas.

Conclusions:

• The developed silver crystals offer superior performance for plasmonic applications.
• This advancement facilitates the creation of advanced, large-area nonlinear plasmonic devices with uniform signal generation.
• The findings pave the way for new possibilities in integrated and cascaded plasmonic systems.