Rainbow of Colors in Photonic Fibers (image) Harvard University Caption The photonic fibers are made by wrapping multiple layers of polymer around a glass core, which is later etched away. The thickness of the layers determines the apparent color of the fiber, which can range across the entire visible spectrum of light. Credit Image courtesy of Mathias Kolle. Usage Restrictions None 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.