Reversible strong coupling in silver nanoparticle arrays using photochromic molecules

Area of Science:

• Plasmonics
• Molecular Photonics
• Materials Science

Background:

• Strong coupling in light-matter interactions is crucial for novel optical phenomena.
• Controlling molecular states with plasmonic fields offers pathways to advanced optoelectronic devices.

Purpose of the Study:

• To demonstrate and analyze a reversible strong coupling regime between dipolar surface plasmon resonance and molecular excited states.
• To investigate the role of photochromic molecules in achieving tunable light-matter interactions.

Main Methods:

• Experimental observation using silver nanoparticle arrays in a polymer film with photochromic molecules.
• Extinction measurements to detect Rabi splitting.
• Derivation of an analytical model for confirmation.

Main Results:

• A clear Rabi splitting of 294 meV was observed, representing ~13% of the molecular transition energy.
• Spectral matching between polymer absorption and plasmonic resonance was found to be critical for coupled states.
• Reversibility was confirmed by cycling photochromic molecules between isomeric forms.

Conclusions:

• A reversible strong coupling regime between surface plasmon resonance and molecular excited states has been successfully demonstrated.
• The findings highlight the importance of spectral overlap and photochromic switching for controlling light-matter interactions.
• This work paves the way for developing switchable plasmonic devices.