Upconversion fiber-optic confocal microscopy under near-infrared pumping

Area of Science:

• Optics and Photonics
• Materials Science
• Biomedical Imaging

Background:

• Upconversion microscopy offers advantages for deep tissue imaging.
• Conventional confocal microscopes often require visible light excitation, limiting penetration depth.
• Rare-earth-doped materials enable efficient nonlinear optical processes.

Purpose of the Study:

• To design and demonstrate a simple upconversion fiber-optic confocal microscope.
• To utilize near-infrared (NIR) excitation for enhanced imaging capabilities.
• To achieve high upconversion fluorescence efficiency and resolution.

Main Methods:

• A fiber-optic confocal microscope was designed using a NIR laser source.
• Rare-earth-doped glass powder was employed as the upconversion material.
• Nonlinear optical frequency conversion was utilized for signal generation.

Main Results:

• The system demonstrated high upconversion fluorescence efficiency (>2%) at a 1.55 µm NIR pumping wavelength.
• The design is compatible with conventional Silicon (Si) detectors.
• Achieved lateral and axial resolutions of ≤1.10 µm and ≤13.11 µm, respectively.

Conclusions:

• The developed upconversion fiber-optic confocal microscope is a simple yet effective design.
• NIR excitation and efficient upconversion enable advanced imaging with conventional detectors.
• The system offers promising performance for various microscopy applications.