A customizable class of colloidal-quantum-dot spasers and plasmonic amplifiers.

Area of Science:

• Nanophotonics and Quantum Technologies
• Materials Science and Engineering

Background:

• Colloidal quantum dots (CQDs) are tunable light emitters used in various optoelectronic devices.
• Spasers, which generate surface plasmons, traditionally required a single material for both gain and cavity, limiting integration of CQDs.
• Existing spaser designs face challenges in accommodating nanomaterials and integrating into larger plasmonic circuits.

Purpose of the Study:

• To develop a versatile quantum dot-based spaser architecture.
• To decouple the gain medium from the plasmonic cavity for enhanced functionality.
• To enable controlled generation, extraction, and manipulation of surface plasmons.

Main Methods:

• Fabrication of aberration-corrected plasmonic cavities with high quality factors on silver substrates.
• Integration of CQDs into cavities using electrohydrodynamic printing and drop-casting.
• Photoexcitation under ambient conditions to generate monochromatic surface plasmons.

Main Results:

• Demonstrated monochromatic surface plasmons with a 0.65-nm linewidth at 630 nm and a quality factor of approximately 1000.
• Successfully generated and extracted surface plasmons above threshold.
• Integrated an amplifier to direct and focus plasmons, generating intense electromagnetic fields.

Conclusions:

• The developed open architecture enables a versatile class of CQD-based spasers.
• This platform allows for controlled manipulation of surface plasmons for fundamental studies and applications.
• The device platform is adaptable to different wavelengths, scales, and geometries for large-area plasmonic chips.