Temperature increase effects on a double-pass cavity type II second-harmonic generation: a model for depleted...

Area of Science:

• Nonlinear optics
• Laser physics
• Materials science

Background:

• Second-harmonic generation (SHG) is a key process for frequency conversion in lasers.
• Double-pass cavities enhance SHG efficiency but can be sensitive to environmental factors like temperature.
• Understanding thermal effects is critical for stable and efficient laser system design.

Purpose of the Study:

• To investigate the impact of temperature increase on the efficiency of type II second-harmonic generation (SHG) in a double-pass cavity.
• To develop and utilize a depleted wave model for simulating continuous-wave SHG with Gaussian beams.
• To quantify the reduction in SHG efficiency caused by thermal-induced phase mismatch.

Main Methods:

• Developed a depleted wave model comprising six coupled equations for a type II double-pass cavity SHG.
• Incorporated the effect of temperature increase by modeling optical absorption and the resulting phase mismatch due to refractive index changes.
• Solved the coupled equations simultaneously, considering fundamental beam depletion, using a custom Intel Fortran code.

Main Results:

• Simulations demonstrated a decrease in SHG efficiency as the nonlinear crystal temperature increased by 5 K, 10 K, and 15 K.
• Observed dramatic reductions in SHG efficiency even with small temperature variations.
• The model's predictions showed excellent agreement with existing experimental data.

Conclusions:

• Temperature increase significantly degrades the efficiency of type II double-pass cavity SHG.
• Thermal management is crucial for maintaining high performance in SHG systems.
• The developed depleted wave model accurately predicts the detrimental effects of temperature on SHG efficiency.