Enhanced performance of thin-disk lasers by pumping into the zero-phonon line

Area of Science:

• Laser physics
• Materials science
• Optics

Background:

• Traditional pumping of Yb:YAG and Yb:LuAG lasers at 940 nm generates significant heat.
• Thermally induced phase distortions lead to diffraction losses, limiting laser efficiency.

Purpose of the Study:

• To investigate the impact of pumping Yb:YAG and Yb:LuAG lasers at the zero-phonon line (969 nm) on heat generation and overall efficiency.
• To demonstrate improved performance in thin-disk laser configurations.

Main Methods:

• Utilized a 969 nm pump wavelength for Yb:YAG and Yb:LuAG lasers.
• Compared performance metrics (heat generation, Stokes efficiency, optical efficiency, M² factor) with conventional 940 nm pumping.
• Tested in both fundamental-mode and multimode thin-disk laser setups.

Main Results:

• Reduced heat generation by 32% compared to 940 nm pumping.
• Increased Stokes efficiency by 3%.
• Achieved 742 W output power with M²≈1.5 and 58.5% optical efficiency in an Yb:LuAG thin-disk laser.
• Reached 72% maximum optical efficiency for multimode Yb:YAG thin-disk lasers (M²≈15).

Conclusions:

• Pumping at 969 nm significantly suppresses thermal load and reduces diffraction losses.
• This pumping strategy offers a substantial increase in overall efficiency for thin-disk lasers.
• The results demonstrate a new, highly efficient pumping scheme for Yb-doped lasers.