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

TL;DR

This paper demonstrates a highly efficient on-chip source of visible-near-IR photon pairs using thin-film lithium niobate nanophotonic waveguides, enabling brighter sources at shorter wavelengths for quantum technologies.

Contribution

The authors present the first high-brightness, on-chip photon pair source at visible-near-IR wavelengths with efficiency comparable to telecom sources, using thin-film lithium niobate nanophotonics.

Findings

Photon pair generation rate of 1.6e9 pairs/mW/nm.

On-chip source efficiency of 2.3e11 pairs/mW.

Shortest wavelength photon pairs in a nanophotonic waveguide to date.

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 ($(1.6 \pm 0.3) \times 10^{9}$ pairs/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. The measured on-chip source efficiency of $(2.3\pm 0.5) \times 10^{11}$ pairs/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. These results represent the shortest wavelength of photon pairs generated in a nanophotonic waveguide reported to date by nearly an octave.