Proximal selenium co-doping in Er:CaF₂ crystal for efficient 2.75 µm lasers.

Area of Science:

• Materials Science
• Laser Physics
• Solid-State Chemistry

Background:

• Non-radiative relaxation is a major limitation in erbium-based mid-infrared lasers.
• Developing novel materials is crucial for overcoming performance bottlenecks in laser technology.

Purpose of the Study:

• To investigate the impact of anion-engineering on erbium-doped fluorite crystals for laser applications.
• To demonstrate efficient mid-infrared laser operation using a modified crystal structure.

Main Methods:

• Co-doping CaF2 crystals with Erbium (Er) and Selenium (Se).
• Characterization of luminescence properties and lifetimes.
• First-principles calculations to understand crystal lattice dynamics and ion interactions.
• Laser performance testing under different pumping schemes.

Main Results:

• Er,Se-co-doped CaF2 exhibited extended lifetimes compared to Er:CaF2.
• First-principles calculations revealed Se2- proximity to Er3+ clusters and introduced low-frequency phonon modes.
• Achieved efficient 2.75 µm continuous-wave laser operation.
• Demonstrated high slope efficiencies of 34.4% (976 nm pumping) and 12.2% (1532 nm pumping).

Conclusions:

• Anion-engineering via Se-doping effectively suppresses non-radiative relaxation in Er:CaF2 lasers.
• This approach facilitates efficient mid-infrared laser operation.
• The study highlights the potential of anion-engineering for designing advanced laser materials.