There are many potentially interesting phenomena that can be obtained with wave refraction in the "wrong" direction, what is commonly now referred to as negative refraction. All sorts of physically new operations and devices come to mind, such as new beam controlling components, re?ectionless interfaces, ?at lenses, higher quality lens or "super lenses," reversal of lenses action, new imaging components, redistribution of energy density in guided wave components, to name only a few of the possibilities. Negative index materials are generally, but not always associated with negative refracting...