Highly efficient 110-W closed-cycle cryogenically cooled Nd:YAG laser operating at 946  nm

Area of Science:

• Laser Physics
• Solid-State Lasers
• Materials Science

Background:

• High-power diode-pumped solid-state lasers are crucial for various applications.
• Achieving high efficiency and output power in lasers, particularly at specific wavelengths like 946 nm, presents significant challenges.
• Nd:YAG lasers are widely used but require efficient pumping and cooling for optimal performance.

Purpose of the Study:

• To report a new record power and efficiency for a 946 nm Nd:YAG laser.
• To demonstrate a practical laser system capable of sustained operation.
• To investigate the impact of cryo-cooling and direct in-band pumping on laser performance.

Main Methods:

• Utilized a closed-cycle acoustic Stirling cryostat to cool the Nd:YAG gain medium to approximately 80 K.
• Employed direct in-band pumping at 868 nm using a volume-Bragg-grating stabilized diode laser bar.
• Characterized laser output power and efficiency with respect to absorbed pump power and incident power.

Main Results:

• Achieved a record output power exceeding 110 W with a power density of 5 TWm⁻²sr⁻¹.
• Demonstrated a slope efficiency of 80% with respect to absorbed pump power.
• Attained an optical-to-optical efficiency of 74% with respect to incident pump power.

Conclusions:

• The developed 946 nm Nd:YAG laser system sets new benchmarks for power and efficiency.
• Cryo-cooling and direct in-band pumping are effective strategies for enhancing laser performance.
• The system exhibits stable daily operation, comparable to conventional water-cooled systems.