Fig. 1
From: Superfluid motion and drag-force cancellation in a fluid of light
Realization of a fluid of light in a propagating geometry and nonlinear response of the bulk crystal. a Sketch of the fluid of light (red beam) flowing past an obstacle (green beam). The input velocity v of the fluid of light is proportional to the input angle θin. The sound velocity cs depends on the intensity If of the red beam. b Blue curve. Calculated optical-index variation Δn with respect to a laser intensity I for the nonlinear photorefractive response of the medium. Red dashed curve. Corresponding sound velocity cs. c Experimental setup. The green beam is shaped by the spatial light modulator (SLM) to create a z-invariant optical defect acting as a localized obstacle in the transverse plane. The red beam is a large gaussian beam and creates the fluid of light. If is controlled by a half-waveplate (HWP) and a polarizer (P). θin is tuned by rotating a mirror (M) imaged at the input of the crystal via a telescope. Both are propagating simultaneously through a biased SBN photorefractive crystal and imaged on a sCMOS camera. The white light controls the saturation intensity of the crystal
