Point-Excitation Wide-Field Upconversion Imaging via a Holographic Polymer Waveguide

Area of Science:

• Materials Science
• Optics
• Photonics

Background:

• Upconversion functionality is promising for high-security encryption and data diversification.
• Limited active areas hinder practical upconversion imaging applications.

Purpose of the Study:

• To overcome the limited active area challenge in upconversion imaging.
• To develop a facile upconversion imaging system with an expanded imaging region.
• To enable advanced high-security image encryption and anticounterfeiting technologies.

Main Methods:

• Designed a holographic polymer waveguide using liquid crystals (LCs) and dithienylethene (DTE) as the high-refractive-index phase.
• Embedded upconversion nanoparticles in a polymer matrix as the low-refractive-index phase.
• Investigated the synergistic effects of LCs and DTE on waveguiding and holographic structure formation.

Main Results:

• Successfully transformed upconversion emission from a localized point to a macroscopic area, expanding the imaging region by up to 225 times.
• Demonstrated the crucial synergy between LCs and DTE for effective waveguiding and holographic waveguide formation.
• Achieved triple-mode image encryption by integrating solidified holograms with rewritable upconversion and photochromic images.

Conclusions:

• The developed holographic polymer waveguide significantly expands the active area for upconversion imaging.
• The synergistic interaction between LCs and DTE is key to the material's performance.
• This technology opens new possibilities for high-security anticounterfeiting applications.