Efficient and tunable frequency conversion using periodically poled thin-film lithium tantalate nanowaveguides

Area of Science:

• Photonics
• Nonlinear Optics
• Materials Science

Background:

• Thin-film lithium tantalate (TFLT) offers superior properties over thin-film lithium niobate for integrated photonics.
• Key advantages include reduced photorefraction, higher optical damage threshold, broader transparency, and lower birefringence.
• These characteristics make TFLT a strong candidate for chip-scale nonlinear optical devices.

Purpose of the Study:

• To demonstrate the first functional second harmonic generator (SHG) using TFLT.
• To leverage high-fidelity poling in z-cut TFLT waveguides for efficient nonlinear frequency conversion.
• To establish a low-loss integrated photonic platform based on TFLT.

Main Methods:

• Fabrication of z-cut TFLT waveguides on an integrated photonic platform.
• High-fidelity poling of the TFLT material to achieve quasi-phase matching.
• Characterization of second harmonic generation efficiency and temperature tunability.

Main Results:

• Achieved strong second harmonic generation with a normalized efficiency of 229 %/(W·cm²).
• Demonstrated an absolute conversion efficiency of 5.5 % at 700 µW pump power.
• Observed stable temperature tunability of -0.44 nm/°C for precise frequency alignment.

Conclusions:

• The developed TFLT SHG is a significant advancement in chip-scale nonlinear optics.
• The device's high efficiency and stable tunability are crucial for applications like atomic clocks and quantum frequency conversion.
• TFLT presents a highly promising platform for future integrated photonic devices.