Mid-Infrared Photon-Pair Generation in AgGaS\(_2\)

We demonstrate non-degenerate photon-pair generation by spontaneous parametric down conversion in a silver gallium sulfide AgGaS\(_2\) crystal. By tuning the pump wavelength, we achieve phase matching over a large spectral range. This allows to generate idler photons in the mid-infrared spectral range above 6 \(\mu m\) wavelength with corresponding signal photons in the visible. Also, we show photon pair generation with broad spectral bandwidth. These results are a valuable step towards the development of quantum imaging and sensing techniques in the mid-infrared.