Continuous-wave and passively Q-switched cryogenic Yb:KLu(WO₄)₂ laser

Area of Science:

• Solid-state laser physics
• Laser engineering
• Materials science

Background:

• Cryogenic cooling enhances laser performance by reducing thermal effects and improving optical properties.
• Yb-doped tungstate crystals are promising gain media for high-power lasers.
• Volume Bragg Grating (VBG) stabilized diode lasers offer precise wavelength control for efficient pumping.

Purpose of the Study:

• To investigate the cryogenic laser performance of an Yb-doped KLu(WO4)2 crystal.
• To evaluate the crystal's efficiency in both continuous-wave (CW) and passively Q-switched operation.
• To determine optimal operating parameters for high output power and energy.

Main Methods:

• Pumping an Yb:KLu(WO4)2 crystal with a VBG-stabilized diode laser at 981 nm.
• Operating the laser in a cryogenic environment (80-100 K).
• Employing a Cr:YAG crystal for passive Q-switching experiments.

Main Results:

• Maximum CW output power of 4.31 W achieved at 80 K with 44.0% slope efficiency.
• Passively Q-switched operation yielded an average output power of 2.11 W at 100 K and 19 kHz.
• Q-switched pulses had an energy of 111 µJ, duration of 231 ns, and peak power of 0.48 kW.

Conclusions:

• Yb:KLu(WO4)2 is a highly efficient gain medium for cryogenic laser applications.
• The crystal demonstrates excellent performance in both CW and Q-switched modes.
• Cryogenic operation significantly boosts laser output power and efficiency.