A device for modifying light distribution includes a transparent body including a first surface, a second surface on an opposite side of the transparent body, and a third surface joining the first surface. The second surface defines a cavity opening away from the first surface. The second surface reflects, towards the third surface, at least a part of light received via the first surface. The third surface reflects, towards the second surface, the light reflected from the second surface. The second surface acts as a light egress surface for the light reflected from the third surface. The third surface includes a groove so that a part of the light reflected from the second surface propagates across the groove prior to being reflected from the third surface. The light distribution can be tuned by adjusting the shape, the size, and/or the location of the groove.