Large Fluorescence Enhancement via Lossless All-Dielectric Spherical Mesocavities

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Nano- and microparticles are widely used to amplify optical signals, particularly fluorescence.
• Plasmonic particles are common but suffer from nonradiative Ohmic losses, limiting their efficiency.

Purpose of the Study:

• To investigate fluorescence enhancement using homogeneous, lossless, all-dielectric spheres in the mesoscale range.
• To explore the impact of intrinsic quantum yield and fluorophore location on fluorescence enhancement.
• To analyze the potential of dielectric spheres for various optical applications.

Main Methods:

• Theoretical analysis of fluorescence enhancement by dielectric spheres.
• Modeling of fluorescence enhancement factor (F) as a function of intrinsic quantum yield (q0).
• Consideration of fluorophore placement (inside or outside the particle).

Main Results:

• Mesoscale dielectric spheres achieve fluorescence enhancements up to F ~ 10^4.
• Absence of Ohmic losses allows F to increase, decrease, or remain unchanged with increasing q0.
• Fluorescence enhancement is tunable by fluorophore location relative to the particle.

Conclusions:

• Lossless dielectric spheres offer a promising alternative to plasmonic particles for fluorescence enhancement.
• The mesoscale range provides unique opportunities for controlling optical properties.
• Potential applications include advanced imaging, molecular sensing, light coupling, and quantum information processing.