Efficient photon-pair generation in layer-poled lithium niobate nanophotonic waveguides

Area of Science:

• Quantum Optics
• Nanophotonics
• Materials Science

Background:

• Integrated photon-pair sources are vital for scalable photonic quantum systems.
• Thin-film lithium niobate is a promising platform, but faces fabrication and efficiency challenges with existing methods like periodically poled lithium niobate (PPLN) and modal phase matching (MPM).

Purpose of the Study:

• To introduce and demonstrate a novel layer-poled lithium niobate (LPLN) nanophotonic waveguide for efficient on-chip photon-pair generation.
• To overcome the limitations of PPLN and conventional MPM in terms of fabrication reliability, device repeatability, and nonlinear interaction efficiency.

Main Methods:

• Utilizing layer-wise polarity inversion through electrical poling in LPLN waveguides to break spatial symmetry.
• Leveraging enhanced nonlinear interactions for MPM and a cascaded second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC) process.
• Characterizing the normalized SHG conversion efficiency and photon-pair generation brightness.

Main Results:

• Achieved a normalized SHG conversion efficiency of 4615% W⁻¹cm⁻² in LPLN waveguides.
• Demonstrated photon-pair generation with a normalized brightness of 3.1 × 10⁶ Hz nm⁻¹mW⁻² in a 3.3 mm LPLN waveguide.
• LPLN waveguides exhibit enhanced fabrication reliability and reduced sensitivity to geometric variations and temperature fluctuations compared to PPLN.

Conclusions:

• LPLN nanophotonic waveguides offer a promising solution for efficient on-chip nonlinear wavelength conversion and non-classical light generation.
• The developed LPLN platform surpasses existing on-chip sources in performance and reliability.
• Immediate applications include quantum communication, quantum networking, and on-chip photonic quantum information processing.