A light transmitting element such as a scintillating element (50) or an optic fiber (50′) has side surfaces coated with a metamaterial (62) which has an index of refraction less than 1 and preferably close to zero to light transmitted in the light transmitting element. A photonic crystal (80) or metamaterial layer optically couples a light output face of the light transmitting element with a light sensitive element (52), such as a silicon photomultiplier (SiPM). A thin metal layer (64) blocks optical communication between adjacent scintillating elements (50) in a radiation detector (22), such as a radiation detector of a nuclear imaging system (10).