High-efficiency nonlinear frequency conversion enabled by optimizing the ferroelectric domain structure in x-cut LNOI...

Area of Science:

• Photonics
• Materials Science
• Quantum Information

Background:

• Ferroelectric domain engineering in thin film lithium niobate is crucial for photonic devices in classical and quantum information processing.
• Periodic poling of ridge waveguides offers advantages over selective etching but faces challenges in fabricating high-quality ferroelectric domains.

Purpose of the Study:

• To optimize the fabrication of high-quality ferroelectric domains in lithium niobate ridge waveguides.
• To enhance nonlinear frequency conversion efficiency in periodically poled nano-waveguides.

Main Methods:

• Optimized applied electric field distribution for domain engineering.
• Characterized inverted domains using second harmonic confocal microscopy, piezoresponse force microscopy, and chemical selective etching.
• Investigated nonlinear frequency conversion via second harmonic generation.

Main Results:

• Achieved rectangular inverted domain structures in ridge waveguides, suitable for efficient nonlinear frequency conversion.
• Measured a normalized conversion efficiency of 1,720 % W⁻¹ cm⁻² for second harmonic generation.
• The achieved efficiency is approximately 60% of the theoretical value.

Conclusions:

• The developed fabrication technique successfully creates high-quality ferroelectric domains in lithium niobate ridge waveguides.
• This method is promising for developing high-efficiency, low-loss lithium niobate nonlinear photonic devices.
• The findings contribute to advancements in photonic devices for information processing.