Lasing action in strongly coupled plasmonic nanocavity arrays

Area of Science:

• Plasmonics
• Nanophotonics
• Laser Physics

Background:

• Photonic band-edge lasers offer feedback but suffer from low modulation speeds and limited mode confinement.
• Plasmonic nanolasers provide ultrafast dynamics and small mode volumes but face challenges with radiative losses and beam directionality.

Purpose of the Study:

• To achieve lasing action from band-edge lattice plasmons in arrays of plasmonic nanocavities.
• To overcome the limitations of existing laser technologies by enabling directional emission and nanoscale light sources.

Main Methods:

• Fabrication and optical pumping of 2D arrays of plasmonic gold or silver nanoparticles.
• Utilizing a semi-quantum electromagnetic approach for simulating optical responses.
• Employing femtosecond-transient absorption spectroscopy to verify enhanced spontaneous emission rates.

Main Results:

• Observed directional beam emission (<1.5° divergence, <1.3 nm linewidth) from nanoparticle arrays.
• Demonstrated behavior as arrays of nanoscale light sources in the near-field.
• Verified stimulated energy transfer to band-edge lattice plasmons and a 200-fold enhancement in spontaneous emission rate.

Conclusions:

• Band-edge lattice plasmons in plasmonic nanoparticle arrays enable directional lasing.
• This approach offers a promising route for developing advanced nanoscale light sources with improved beam characteristics.
• The findings pave the way for applications requiring efficient and directional light emission from subwavelength structures.