Photonic-plasmonic mode coupling in on-chip integrated optoplasmonic molecules

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Whispering gallery mode (WGM) resonators offer enhanced light confinement.
• Noble metal nanostructures exhibit localized surface plasmon resonances (LSPRs).
• Integrating photonic and plasmonic elements is key for novel optical functionalities.

Purpose of the Study:

• To investigate photonic-plasmonic mode coupling in a new class of on-chip optoplasmonic materials.
• To fabricate and characterize optoplasmonic molecules with precisely positioned dielectric microspheres and metal nanostructures.
• To explore the synergistic interaction between WGMs and LSPRs.

Main Methods:

• Fabrication of optoplasmonic molecules using top-down methods and template-guided self-assembly.
• Precise positioning of plasmonic nanostructures (gold nanoparticles) relative to dielectric microspheres.
• Characterization via far-field scattering spectroscopy.
• Validation and analysis using generalized multiple particle Mie theory simulations.

Main Results:

• Observed broadening of TE and TM modes in scattering spectra, indicating efficient mode coupling.
• Experimental evidence of coupling between WGM photonic modes and LSPR plasmonic modes.
• Simulations confirmed hybrid mode formation and spatial field distributions.
• Significant enhancement (approx. 2 orders of magnitude) of local electric field intensity on gold nanoparticles.

Conclusions:

• Demonstrated efficient photonic-plasmonic mode coupling in well-defined optoplasmonic molecules.
• The hybrid modes exhibit enhanced fields localized on the plasmonic nanostructures.
• This platform enables advanced control over light-matter interactions for future photonic devices.