Refraction of space-time wave packets: III. Experiments at oblique incidence

Abstract: The refraction of space-time (ST) wave packets at planar interfaces between non-dispersive, homogeneous, isotropic dielectrics exhibit fascinating phenomena, even at normal incidence. Examples of such refractive phenomena include group-velocity invariance across the interface, anomalous refraction, and group-velocity inversion. Crucial differences emerge at oblique incidence with respect to the results established at normal incidence. For example, the group velocity of the refracted ST wave packet can be tuned simply by changing the angle of incidence. In paper (III) of this sequence, we present experimental verification of the refractive phenomena exhibited by ST wave packets at oblique incidence that were predicted in paper (I). We also examine a proposal for 'blind synchronization' whereby identical ST wave packets arrive simultaneously at different receivers without \textit{a priori} knowledge of their locations except that they are all located at the same depth beyond an interface between two media. A first proof-of-principle experimental demonstration of this effect is provided.