1d3d (IMAGE) Kazan Federal University Caption Schemes of PPC with equal effective refractive index and structure period. a 1D PPC and b 3D opal-like PPC Credit Kazan Federal University 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.