Broadband quantum photon source in a step-chirped periodically poled lithium niobate waveguide

Area of Science:

• Nonlinear Optics
• Quantum Optics
• Materials Science

Background:

• Broadband nonlinear optical devices are essential for classical and quantum optics.
• Periodically poled lithium niobate (PPLN) is a key material for nonlinear optical applications.

Purpose of the Study:

• To design and fabricate a novel step-chirped PPLN waveguide.
• To demonstrate its capability for broadband second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC).

Main Methods:

• Fabrication of a 6.82-mm-long step-chirped PPLN waveguide on lithium niobate on insulator.
• Characterization of SHG efficiency and SPDC bandwidth and brightness.

Main Results:

• Achieved an average SHG efficiency of 91%/W/cm² over 1510 nm-1620 nm.
• Demonstrated broadband photon-pair generation with a maximum full bandwidth of 99 THz (846 nm) and brightness of 21 MHz/mW/nm.
• Enabled SPDC across a wide range of pump wavelengths.

Conclusions:

• The developed waveguide offers an efficient and experiment-friendly approach for broadband photon pair generation.
• This technology holds significant promise for advancing quantum metrology.
• The device enables quasi-phase matching over a broad bandwidth.