I mis-wrote. I meant to put reverse refraction, referring to recent discoveries that certain materials can be forced to "bend" light the opposite way that a prism or some other object would normally be expected to.
I am to give my first physics talk for a seminar class next week and I am looking for info on recent research done on the reverse diffraction phenomenon. Any links or thoughts would be appreciated. (Credible sources only please, as this is for a class).