Highly efficient visible and near-IR photon pair generation with thin-film lithium niobate

Creators: Harper, Nathan A.; Hwang, Emily Y.; Sekine, Ryoto; Ledezma, Luis; Perez, Christian; Marandi, Alireza¹; Cushing, Scott K.¹

1. California Institute of Technology

Abstract

Efficient on-chip entangled photon pair generation at telecom wavelengths is an integral aspect of emerging quantum optical technologies, particularly for quantum communication and computing. However, moving to shorter wavelengths enables the use of more accessible silicon detector technology, and opens up applications in imaging and spectroscopy. Here, we present high brightness ((1.6 ± 0.3) × 10⁹ pairs/s/mW/nm) visible–near-IR photon pair generation in a periodically poled lithium niobate nanophotonic waveguide. The degenerate spectrum of the photon pairs is centered at 811 nm with a bandwidth of 117 nm when pumped with a spectrally multimode laser diode. The measured on-chip source efficiency of (2.3 ± 0.5) × 10¹¹ pairs/s/mW is on par with source efficiencies at telecom wavelengths and is also orders of magnitude higher than the efficiencies of other visible sources implemented in bulk crystal or diffused waveguide-based technologies. Further improvements in the brightness and efficiencies are possible by pumping the device with a single-frequency laser, which would also shrink the pair bandwidth. These results represent the shortest wavelength of photon pairs generated in a nanophotonic waveguide reported to date by nearly an octave.

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Acknowledgement

The authors gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute (KNI) and the Beckman Biological Imaging Facility at Caltech. This work was additionally supported by the KNI-Wheatley Scholar in Nanoscience and the Rothenberg Innovation Initiative. N.A.H. was supported by the Department of Defense (DoD) through the National Defense Science and Engineering Graduate (NDSEG) Fellowship Program. E.Y.H. was supported by the National Science Foundation Graduate Research Fellowship Program under Grant no. DGE-1745301. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors(s) and do not necessarily reflect the views of the National Science Foundation.

Funding

Air Force Office of Scientific Research (FA9550-20-1-0040); Army Research Office (W911NF-23-1-0048); U.S. Department of Energy (DE-SC0020151); National Science Foundation (DGE-1745301, EECS 1846273).

Data Availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

See Supplement 1 for supporting content.

Conflict of Interest

The authors declare no conflicts of interest.

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