High-efficiency watt-level continuous-wave 2.9  μm Ho,Pr:YLF laser.

Area of Science:

• Solid-state laser physics
• Mid-infrared photonics
• Materials science

Background:

• Ho³⁺ lasers at 2.9 μm face a bottleneck due to shorter upper-level lifetimes compared to lower-level lifetimes.
• Efficient laser operation requires overcoming this population inversion challenge.

Purpose of the Study:

• To develop high-efficiency, continuous-wave 2.9 μm laser emission.
• To investigate the effect of co-doping Ho³⁺ and Pr³⁺ ions in YLiF₄ (YLF) crystals.
• To optimize doping concentrations for enhanced laser performance.

Main Methods:

• Fabrication of novel Ho³⁺,Pr³⁺:YLF crystals with optimized doping ratios.
• Utilizing as-grown crystals with specific doping concentrations (0.498 at.% Ho³⁺, 0.115 at.% Pr³⁺ and 0.489 at.% Ho³⁺, 0.097 at.% Pr³⁺) as gain media.
• Pumping the crystals with a 1150 nm fiber laser to achieve continuous-wave operation.

Main Results:

• High-efficiency, continuous-wave 2.9 μm laser operations were achieved using both co-doped YLF crystals.
• The Ho³⁺,Pr³⁺:YLF crystal (0.498 at.% Ho³⁺, 0.115 at.% Pr³⁺) produced a maximum output power of 1.27 W with a 28.3% slope efficiency.
• This represents the highest output power reported for Ho³⁺-doped 2.9 μm lasers to date.

Conclusions:

• Co-doping Ho³⁺ and Pr³⁺ ions effectively overcomes the lifetime bottleneck in 2.9 μm laser emission.
• Ho,Pr:YLF crystals demonstrate significant potential for developing high-power and high-efficiency mid-infrared lasers.
• Optimized doping concentrations are crucial for achieving superior laser performance.