Quantum 2025 – scientific programme

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THU: Thursday Contributed Sessions

THU 13: Poster Session: Applications

THU 13.45: Poster

Thursday, September 11, 2025, 16:30–18:30, ZHG Foyer 1. OG

Towards realizing a single mode fiber wavelength division multiplexer for quantum frequency conversion — •Zoë Matti, Marlon Schäfer, Felix Rohe, David Lindler, Tobias Bauer, and Christoph Becher — Universität des Saarlandes, Fachrichtung Physik, Campus E2 6, 66123 Saarbrücken

Quantum networks using preexisting optical fiber infrastructure require photons with wavelengths in the low-loss telecom bands. As most quantum memories show optical transitions in the visible to near-infrared, quantum frequency conversion, i.e. a nonlinear difference frequency mixing process, of single photons to telecom wavelengths is regarded as a key enabling technology. Achieving near-unity internal conversion efficiencies requires a high spatial overlap of the single photon signal and the mixing wave. While devices based on free-space optics have been demonstrated, a large scale deployment would benefit greatly from a robust and compact fiber-based design. However, overlapping the single photons with the mixing wave in the fundamental mode of a nonlinear waveguide becomes particularly challenging when the interacting wavelengths differ significantly.
Here we investigate an approach for a single-mode fiber wavelength division multiplexer (WDM), combining the visible single photon and mid-infrared mixing beam into an endlessly single-mode photonic crystal fiber (PCF). We show initial results using a commercially available WDM spliced to a PCF and present simulations of the spatial mode profiles of the guided modes in the SMF28 fiber and the PCF to estimate the lowest attainable insertion loss.

Keywords: nonlinear optics; photonic crystal fiber