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Atomic spin-controlled non-reciprocal Raman amplification of fibre-guided light


In a non-reciprocal optical amplifier, gain depends on whether the light propagates forwards or backwards through the device. Typically, one requires either the magneto-optical effect, temporal modulation or optical nonlinearity to break reciprocity. By contrast, here we demonstrate non-reciprocal amplification of fibre-guided light using Raman gain provided by spin-polarized atoms that are coupled to the nanofibre waist of a tapered fibre section. The non-reciprocal response originates from the propagation-direction-dependent local polarization of the nanofibre-guided mode in conjunction with polarization-dependent atom–light coupling. We show that this novel mechanism can also be implemented without an external magnetic field and that it allows us to fully control the direction of amplification via the atomic spin state. Our results may simplify the construction of complex optical networks. Moreover, by using other suitable quantum emitters, our scheme could be implemented in photonic integrated circuits and circuit quantum electrodynamics.

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Fig. 1: Schematic of experimental setup.
Fig. 2: Non-reciprocal Raman gain.
Fig. 3: Magnetic-field-free non-reciprocal Raman gain.

Data availability

Source data for Figs. 2 and 3 are available in an open-access repository39.


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We thank J. Fink, A. Husakou, F. Tebbenjohanns and J. Volz for stimulating discussions and helpful comments. We acknowledge funding by the Alexander von Humboldt Foundation in the framework of the Alexander von Humboldt Professorship endowed by the Federal Ministry of Education and Research. Moreover, financial support from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 800942 (ErBeStA) is gratefully acknowledged.

Author information

Authors and Affiliations



C.L. and S.P. adapted and extended the setup for this experiment and carried out the measurements. S.J. assisted in the early stages of the experiments. Data were analysed and modelled by C.L., S.P. and P.S. The experiment was conceived and supervised by A.R. and P.S. All the authors contributed to the writing of the manuscript.

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Correspondence to Philipp Schneeweiss.

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The authors declare no competing interests.

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Nature Photonics thanks Kanu Sinha, David Wilkowski and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–9, Discussion and Table 1.

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Pucher, S., Liedl, C., Jin, S. et al. Atomic spin-controlled non-reciprocal Raman amplification of fibre-guided light. Nat. Photon. 16, 380–383 (2022).

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