The path toward a large imaging interferometer in the infrared, as proposed within the framework of the Planet Formation Imager initiative, represents an incredibly exciting and complex challenge of future infrared interferometry. In this context, heterodyne detection has been proposed as a potential alternative in order to recombine a large number of telescopes, with kilometric baselines, in a practical infrastructure, despite a poorer sensitivity compared to classical interferometry. Among the different building blocks necessary to an infrared heterodyne interferometer, the detection and correlation of wide-bandwidth signals remains a big obstacle, in particular to gain further in sensitivity. Here, we propose to address the problem of transport and correlation of wide- bandwidth signals over kilometric distances by presenting the concept of a photonic correlation dedicated to infrared heterodyne interferometry. We present the concept, the implementation and the experimental results for the correlation of two signals with a phase modulation implementation, its possible extrapolation to a larger number of telescopes and spectral channels, and an alternative correlation scheme based on amplitude modulation.
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