2.4-watts second-harmonic generation in ppZnO:LN ridge waveguide for lithium laser cooling

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Science and Photonics
• Quantum Technologies

Background:

• Laser cooling of atoms requires stable, single-frequency laser sources at specific wavelengths.
• Lithium atoms are crucial for fundamental physics research and quantum simulations.
• Efficient frequency conversion is key to generating laser light at desired wavelengths.

Purpose of the Study:

• To develop a simple, all-solid-state laser source for laser cooling of lithium atoms.
• To investigate frequency doubling efficiency in a periodically poled zinc oxide-doped lithium niobate (ppZnO:LN) ridge waveguide.
• To analyze thermal effects in the laser system at high fundamental powers.

Main Methods:

• Utilized a diode-pumped solid-state laser as the fundamental light source.
• Employed a ppZnO:LN ridge waveguide for internal second-harmonic generation (frequency doubling).
• Developed a theoretical model to explain observed thermal effects at elevated power levels.
• Compared the performance with an external resonant frequency doubling cavity.

Main Results:

• Achieved 2.4 W of single-frequency light at 671 nm.
• Demonstrated an internal frequency doubling efficiency of 54% in the ppZnO:LN waveguide.
• Characterized thermal effects impacting laser performance at higher fundamental powers.
• An external resonant cavity configuration yielded a more efficient 5.2 W at 671 nm.

Conclusions:

• The developed all-solid-state laser provides a practical source for lithium atom laser cooling.
• ppZnO:LN ridge waveguides offer efficient, integrated frequency doubling capabilities.
• Understanding thermal effects is crucial for optimizing high-power solid-state laser systems.