Visible and near-IR entangled photon generation and UV second harmonic generation with lithium niobate nanophotonic waveguides for on-chip spectroscopy

Emily Y. Hwang; Nathan A. Harper; Ryoto Sekine; Luis Ledezma; Alireza Marandi; Scott K. Cushing

doi:10.1117/12.3000100

12 March 2024 Visible and near-IR entangled photon generation and UV second harmonic generation with lithium niobate nanophotonic waveguides for on-chip spectroscopy

Emily Y. Hwang, Nathan A. Harper, Ryoto Sekine, Luis Ledezma, Alireza Marandi, Scott K. Cushing

Author Affiliations +

Proceedings Volume 12869, Nonlinear Frequency Generation and Conversion: Materials and Devices XXIII; 1286907 (2024) https://doi.org/10.1117/12.3000100
Event: SPIE LASE, 2024, San Francisco, California, United States

Abstract

Entangled photon pairs generated by a low-power continuous-wave laser could replicate pulsed laser-based tabletop spectroscopy by taking advantage of the inherent quantum correlations between the photons. Much of the current work in the thin-film lithium niobate platform has focused on infrared wavelengths, leaving shorter wavelengths still a largely unexplored space, particularly for spectroscopy. In this work, we have fabricated periodically poled lithium niobate nanophotonic waveguides for entangled photon generation through spontaneous parametric downconversion with a visible pump (406 nm). Characterization of the waveguided pair source confirms the spectral and temporal correlations of energy-time entangled photons with an on-chip pair generation efficiency of (2.3 ± 0.5) × 1011 pairs/s/mW, brightness of (1.6 ± 0.3) × 109 pairs/s/mW/nm, and two-photon interference visibility greater than 99%. With the same material platform, we have also demonstrated second harmonic generation with on-chip powers up to 30 μW and wavelengths as low as 355 nm, demonstrating lithium niobate’s potential for ultraviolet nonlinear photonics and frequency doubling in the UV-A spectral region. Through design of larger cross-section waveguides, we have also explored how variations in the lithium niobate thin film thickness can affect quasi-phase matching. To date, this is the first reported demonstration of periodically poled lithium niobate nanophotonic waveguides for spontaneous parametric downconversion at a fully visible pump wavelength (406 nm) as well as second harmonic generation in the UV (355 nm). Future work towards fully on-chip spectroscopy will explore integrating an on-chip Mach-Zehnder interferometer with the entangled photon source.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Emily Y. Hwang, Nathan A. Harper, Ryoto Sekine, Luis Ledezma, Alireza Marandi, and Scott K. Cushing "Visible and near-IR entangled photon generation and UV second harmonic generation with lithium niobate nanophotonic waveguides for on-chip spectroscopy", Proc. SPIE 12869, Nonlinear Frequency Generation and Conversion: Materials and Devices XXIII, 1286907 (12 March 2024); https://doi.org/10.1117/12.3000100

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