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Nonlinear Optics

Efficient Frequency Downconversion at the Single Photon Level from 738 nm to 1557 nm

Sebastian Zaske, Andreas Lenhard, Christoph Becher

Published Jan 1, 2011• 0 citations
Publisher

Abstract

We report on quantum frequency downconversion using a ZnO:PPLN ridge waveguide. An internal conversion efficiency of 73% is achieved. We identify Raman scattering to be the dominant noise source in the frequency converter.
DOI
10.1364/nlo.2011.nmb3

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We demonstrate low-noise and efficient frequency conversion by sum-frequency mixing in a periodically poled LiNbO(3) (PPLN) waveguide. Using a 1556 nm pump, 1302 nm photons are efficiently converted to 709 nm photons. We obtain 70% conversion efficiency in the PPLN waveguide and >50% external conversion efficiency with 600 noise counts per second at peak conversion with continuous-wave pumping. We simultaneously achieve low noise and high conversion efficiency by careful spectral filtering. We discuss the impact of low-noise frequency translation on single-photon upconversion detection and quantum information applications.
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Converting single photons from one wavelength to another is of fundamental interest for future quantum communication and computing. Using commercially available lasers and a multimode PPLN waveguide a DFG scheme was set up. Phase-matching was shown in the fundamental transverse mode of the waveguide for wavelengths between 851 nm and 862 nm. The setup is capable of converting up to 87% of photons from 856 nm to 1526 nm in transverse fundamental mode. Simulations were performed showing that the quantum conversion efficiency at 856 nm is representative for powers down to thousands of photons per second.
Near-infrared single photon sources in telecommunication bands, especially at 1550 nm, are required for long-distance quantum communication. Here a down-conversion quantum interface is implemented, where the single photons emitted from single InAs quantum dot at 864 nm is down converted to 1552 nm by using a fiber-coupled periodically poled lithium niobate (PPLN) waveguide and a 1.95 μmm pump laser, and the frequency conversion efficiency is ∼40%. The single-photon purity of quantum dot emission is preserved during the down-conversion process, i.e., g (2) (0), only 0.22 at 1552 nm. This present technique advances the III–V semiconductor quantum dots as a promising platform for long-distance quantum communication.