9 kilowatt-level direct-liquid-cooled Nd:YAG multi-module QCW laser

Area of Science:

• Laser Physics
• Materials Science

Background:

• High-power lasers are crucial for various industrial and scientific applications.
• Nd:YAG lasers are widely used due to their favorable properties, but achieving high power levels with good beam quality remains a challenge.
• Direct liquid cooling, particularly with heavy water (D2O), offers efficient thermal management for high-power laser systems.

Purpose of the Study:

• To develop and demonstrate a high-average-power, direct-D2O-cooled Nd:YAG thin disk laser resonator.
• To investigate the performance of a multi-disk laser architecture with straight-through geometry.
• To optimize the gain module design for efficient power extraction and thermal management.

Main Methods:

• A 9 kilowatt-level direct-D2O-cooled side-pumped Nd:YAG multi-disk laser resonator was designed and constructed.
• The resonator featured a straight-through geometry with 40 Nd:YAG thin disks and D2O cooling layers at the Brewster angle.
• Detailed analysis of resonator losses and Nd:YAG thin disk design was performed.
• Quasi-Continuous Wave (QCW) mode operation with a pulse width of 250μs was employed.

Main Results:

• The highest pulse energy achieved was over 20 J at a 10 Hz repetition frequency.
• At high repetition frequencies, average output powers of 9.8 kW (stable resonator, ηo-o = 26%) and 9.1 kW (unstable resonator, ηo-o = 21.8%) were obtained.
• Corresponding beam quality factors were βstable = 14.7 and βunstable = 9.5.
• This work represents the first demonstration of a 9 kilowatt-level direct-liquid-cooled Nd:YAG thin disk laser resonator.

Conclusions:

• The direct-D2O-cooled Nd:YAG thin disk laser resonator successfully achieved kilowatt-level average output power.
• The multi-disk architecture and optimized gain module design are effective for high-power laser operation.
• This technology offers a promising solution for applications requiring high-power, efficient laser sources.