Cherenkov radiation and the associated effect that produces it is caused by a charged particle that moves through a medium faster than light can move through that medium. Some people describe it as the sonic boom of light and it is what’s responsible for the eerie blue glow of underwater nuclear reactors. Much like a sonic boom, whatever the particle is travelling through produces a series of decentered circles which produce a forward moving wave as shown below.
What is very hard to imagine is reverse cherenkov radiation. When the medium has been engineered to have a negative permittivity and permeability, even less (if that makes any sense) then that of free space. The radiation is produced backwards with the wave form producing a cone behind instead of in front.
Due to various physical limitations studies on this reverse radiation are sparsely spaced but with various material improvements new experiments are constantly being designed. A recent experiment involved observing the interaction of the radiation at the interface between the different materials in a dielectric. Ways were also presented on how to improve the generation of reverse cherenkov by altering the boundary between the two surfaces in order to produce radiation with a thinner range of frequencies as to more applicable in the future.