Fishnet Metamaterial (IMAGE) University of California - Berkeley Caption On the left is a schematic of the first 3-D "fishnet" metamaterial that can achieve a negative index of refraction at optical frequencies. On the right is a scanning electron microscope image of the fabricated structure, developed by UC Berkeley researchers. The alternating layers form small circuits that can bend light backwards. Credit Image by Jason Valentine, UC Berkeley Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.