Highly Polarized Upconversion Emissions from Lanthanide-Doped LiYF₄ Crystals as Spatial Orientation Indicators

Area of Science:

• Solid-state physics
• Luminescence and spectroscopy
• Materials science

Background:

• Polarized emission is linked to material structure and morphology.
• Polarization mechanisms in lanthanide upconversion (UC) are under-explored.
• Development of highly polarized UC emissions is limited.

Purpose of the Study:

• Investigate polarized UC emissions in lanthanide-doped LiYF4 crystals.
• Explore the potential of these emissions for optical orientation sensing.

Main Methods:

• Studied well-resolved UC emissions from Er3+ and Ho3+ doped LiYF4 crystals.
• Utilized the strong anisotropic crystal field of LiYF4.
• Classified UC emissions based on transition dipole orientation relative to the c-axis.

Main Results:

• Achieved highly polarized UC emissions from Er3+ and Ho3+ in LiYF4.
• Demonstrated classification of UC emissions into two sets based on dipole orientation (parallel or perpendicular to the c-axis).
• Developed a 3D optical orientation sensor utilizing polarized UC emissions.

Conclusions:

• Enhanced understanding of polarized photoluminescence in lanthanide UC systems.
• Established a novel method for 3D orientation sensing using UC polarization.
• Opened new avenues for developing unique UC-based orientation sensors.