different SRR configurations. Research has continued into terahertz radiations with SRRs Other related work fashioned metamaterial configurations with fractals and non-SRR structures. These can be constructed with materials such as periodic metallic crosses, or an ever-widening concentric ring structures known as Swiss rolls. Permeability for only the red wavelength at 780 nm has been analyzed and along with other related work. See also History of metamaterials Superlens Quantum metamaterials Metamaterial cloaking Photonic metamaterials Metamaterial antennas Nonlinear metamaterials Photonic crystal Seismic metamaterials Acoustic metamaterials Metamaterial absorber Plasmonic metamaterials Terahertz metamaterials Tunable metamaterials Transformation optics Theories of cloaking Academic journals Metamaterials (journal) Metamaterials books Metamaterials Handbook Metamaterials: Physics and Engineering Explorations References Further reading Shepard, K. W. et al. Split-ring resonator for the Argonne Superconducting Heavy Ion Booster. IEEE Transactions on Nuclear Science, VoL. NS-24, N0.3, JUN 1977. External links Video: John Pendry lecture: The science of invisibility April 2009, SlowTV Split Ring Resonator Calculator: Online tool to calculate the LC equivalent circuit and resonant frequency of SRR and CSRR topologies. Resonators Materials science Electromagnetic radiation Metamaterials Scattering, absorption and radiative transfer (optics) Optical materials