Planar antenna designs for efficient coupling between a single emitter and an optical fiber

Area of Science:

• Optoelectronics
• Nanophotonics
• Biomedical Sensing

Background:

• Fluorescence detection is crucial for in-vitro diagnostics (IVD).
• Efficiently coupling fluorescence signals into optical fibers for detection remains a significant challenge, often limiting sensitivity to the single-molecule level.
• Existing methods struggle with optimal excitation and signal collection.

Purpose of the Study:

• To investigate fiber geometries, materials, and coatings for efficient fluorescence coupling.
• To combine optical fibers with planar Yagi-Uda antennas for enhanced excitation and collection.
• To achieve high coupling efficiency for sensitive fluorescence detection.

Main Methods:

• Simulated a practical setting involving optical fibers and a planar Yagi-Uda antenna.
• Investigated specific fiber geometries, materials (polyvinyl alcohol - PVA), and coatings.
• Analyzed coupling efficiency for different emitter orientations (horizontal dipole and random).

Main Results:

• Achieved over 70% coupling efficiency for a horizontally oriented dipole emitter at 700 nm embedded in PVA.
• Demonstrated that random emitter orientations reduce coupling efficiency by a factor of 2/3 due to antenna geometry.
• The combined system shows potential for overcoming current limitations in fiber-based fluorescence detection.

Conclusions:

• The developed fiber-antenna system significantly enhances fluorescence coupling efficiency.
• This approach is highly relevant for achieving single-molecule detection using fiber optics.
• Potential applications include advanced IVD, nanoscale light coupling, and high-resolution, low-background imaging techniques.