The joint research group led by Professor Tie Jun Cui, the State Key Laboratory of Millimeter Waves, Southeast University, and Professor David R. Smith, the Department of Electrical and Computer Engineering, Duke University, has made significant progress in the study of electromagnetic concentrators. The group reported their results on Monday, June 30, 2008 in Applied Physics Letters. Their simulation result of the heart-shaped concentrator was chosen as the cover image in this issue.

Electromagnetic concentrator is a novel device, which guides and concentrates the incident electromagnetic waves to enhance the energy density. Such a device has important potential applications in instruments that need high-strength fields, such as solar cells. In the earlier time, the circular electromagnetic concentrator had been reported in a literature, but it is very limited in practical applications. The joint group employed non-uniform rational B-spline curves (NURBS), a powerful mathematical tool, to study electromagnetic concentrators. They have designed arbitrarily-shaped concentrators by using NURBS curves to describe the geometry boundary of an arbitrary object based on the theory of optical transformation. The electromagnetic concentrator could be achieved by the artificial metamaterials, which can provide a new way to amplify the plane waves efficiently. The usage of NURBS will expand the generality of the transformation optics and could make a very general tool to interface with commercial software like 3D STUDIOMAX and MAYA. Hence the transformation optics is possible to become industry.

This work has been supported by the National Natural Science Foundation of China, and the National Basic Research Program of China.