Robust single-frequency 589 nm fiber laser based on phase modulation and passive demodulation

Area of Science:

• Astronomy
• Laser Physics
• Optical Engineering

Background:

• Sodium guide stars are crucial for adaptive optics in astronomy.
• High-power, single-frequency lasers are needed for efficient guide star generation.
• Previous methods faced challenges in power and stability.

Purpose of the Study:

• To develop a robust 20-W continuous-wave (CW) single-frequency 589 nm laser.
• To enable more effective sodium guide star generation for astronomical observations.
• To simplify laser design and enhance operational robustness.

Main Methods:

• Utilized π-depth binary phase modulation on a seed laser.
• Implemented three stages of strain in a gain fiber to suppress stimulated Brillouin scattering (SBS) at 1178 nm.
• Employed a periodically poled lithium tantalate (PPLT) crystal for single-pass frequency doubling.

Main Results:

• Achieved a 20-W CW single-frequency 589 nm laser output.
• Demonstrated a frequency doubling efficiency of up to 41.6%.
• Reported the highest power for CW 589 nm generation via single-pass frequency doubling to date.

Conclusions:

• The developed laser system offers a simplified and robust solution for sodium guide star applications.
• The high-power 589 nm laser output significantly advances capabilities in astronomical adaptive optics.
• The novel SBS suppression technique is key to achieving high-power, single-frequency operation.