Fig. 3
From: Superfluid motion and drag-force cancellation in a fluid of light
Optical analog of the drag force exerted by the fluid and associated displacement of the obstacle. a–e Local intensity difference I+ − I− extracted from the experimental images of the intensity of the fluid-of-light beam measured at the crystal’s output for various input conditions (If ranging from 44 (a) to 349 (e) mW cm−2 and v/cs ranging from −0.41 to 4.10). Inset of e: the original image is cropped around the optical defect and integrated over two regions, downstream (I−) and upstream (I+). The typical integration area is of the order of ξ. The grey dotted line corresponds to v/cs = 0. f–j Measurement of the transverse displacement of the obstacle induced by the local modulation of the intensity of the fluid of light for the same input conditions as for figures a–g. Grey boxes define the typical uncertainty in the measured quantities, the white points in f corresponding to the displacement along the y axis for If = 44 mW cm−2, which is expected to be zero
