Not in a black hole, where it is supposed to constitute the ‘evaporation’ of photons across the hole’s event horizon, but rather, in a refractive index perturbation style event horizon, in the lab. It is made in glass.
… researchers using a CCD camera detected a peculiar kind of photon emission at a 90-degree angle to the glass. … researchers arranged the experiment in a way to strongly suppress or eliminate other types of radiation.
“Experimental evidence of photon emission that on one hand bears the characteristics of Hawking radiation and on the other is distinguishable and thus separate from other known photon emission mechanisms,” the physicists wrote in their study. “We therefore interpret the observed photon emission as an indication of Hawking radiation induced by the analogue event horizon.”