Selectively enhanced Raman/fluorescence spectra in photonic-plasmonic hybrid structures

Area of Science:

• Optics and Photonics
• Materials Science
• Spectroscopy

Background:

• Surface-enhanced spectroscopy (SES) relies on controlling molecular interactions with hybrid photonic-plasmonic structures.
• Optoplasmonic systems, combining optical resonators and plasmonic nanoparticles, offer tunable platforms for SES.

Purpose of the Study:

• To investigate the mode coupling mechanism and surface-enhanced spectroscopy (SES) performance in a polystyrene microsphere (PS MS) and gold nanoparticle (Au NP) hybrid system.
• To understand how the relative positions of molecules, PS MS, and Au NPs influence SES.
• To demonstrate selective enhancement of molecular signals through tailored optoplasmonic structures.

Main Methods:

• Fabrication of an optoplasmonic system using polystyrene microsphere (PS MS) resonators and gold nanoparticles (Au NPs).
• Systematic investigation of mode coupling mechanisms by varying the spatial arrangement of components.
• Characterization of surface-enhanced Raman scattering (SERS) and fluorescence signals from molecules within the hybrid structure.

Main Results:

• Mode coupling and SES performance are highly sensitive to the relative positioning of PS MS, Au NPs, and molecules.
• Two distinct arrangements of the hybrid structure were demonstrated.
• One arrangement supports sharp whispering-gallery modes for fluorescence enhancement, while the other provides significant Raman signal enhancement with low detection limits and robustness.

Conclusions:

• The interplay between enhancement and quenching channels in the PS MS and Au NP system allows for selective signal amplification.
• Tailoring the optoplasmonic architecture enables precise control over spectroscopic signal detection.
• This work provides a pathway for developing advanced SES techniques with improved sensitivity and selectivity.