Thermal dephasing in an enhanced cavity based high-power second harmonic generation

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• Second-harmonic generation (SHG) is crucial for frequency conversion in lasers.
• Thermal dephasing effects in nonlinear crystals can limit SHG efficiency and stability.
• Periodically poled lithium niobate (PPLN) is a key material for efficient SHG.

Purpose of the Study:

• To investigate the performance of an enhanced-cavity (EC) for high-power and efficient SHG.
• To numerically simulate SHG coupled equations considering thermal dephasing.
• To explore methods for optimizing SHG efficiency and mitigating thermal effects.

Main Methods:

• Numerical simulation of coupled equations for SHG.
• Modeling thermal dephasing effects in PPLN crystals embedded in an oven.
• Investigating the impact of PPLN temperature, mirror reflectivity, and pump power.

Main Results:

• Achieved SHG efficiency exceeding 90% under optimal conditions.
• Demonstrated a 15%-50% improvement in SHG efficiency using the EC-SHG device.
• The EC-based SHG device effectively reduces and suppresses thermal dephasing.

Conclusions:

• Enhanced-cavity designs offer a promising approach for high-efficiency and stable SHG.
• Optimizing PPLN temperature, mirror reflectivity, and pump power is critical for maximum SHG performance.
• EC-SHG systems provide superior performance compared to single-pass schemes, particularly in managing thermal effects.