摘要Transformation optics offers remarkable control over electromagnetic fields and opens an exciting gateway to design `invisible cloak devices' recently. We present an important class of two-dimensional (2D) cloaks with polygon geometries. Explicit expressions of transformed medium parameters are derived with their unique properties investigated. It is found that the elements of diagonalized permittivity tensors are always positive within an irregular polygon cloak besides one element diverges to plus infinity and the other two become zero at the inner boundary. At most positions, the principle axes of permittivity tensors do not align with position vectors. An irregular polygon cloak is designed and its invisibility to external electromagnetic waves is numerically verified. Since polygon cloaks can be tailored to resemble any objects, the transformation is finally generalized to the realization of 2D cloaks with arbitrary geometries
Abstract：Transformation optics offers remarkable control over electromagnetic fields and opens an exciting gateway to design `invisible cloak devices' recently. We present an important class of two-dimensional (2D) cloaks with polygon geometries. Explicit expressions of transformed medium parameters are derived with their unique properties investigated. It is found that the elements of diagonalized permittivity tensors are always positive within an irregular polygon cloak besides one element diverges to plus infinity and the other two become zero at the inner boundary. At most positions, the principle axes of permittivity tensors do not align with position vectors. An irregular polygon cloak is designed and its invisibility to external electromagnetic waves is numerically verified. Since polygon cloaks can be tailored to resemble any objects, the transformation is finally generalized to the realization of 2D cloaks with arbitrary geometries
[1] Pendry J B et al 2006 Science 312 1780 [2] Schurig D et al 2006 Science 314 977 [3] Schurig D et al 2006 Opt. Express 14 9794 [4] Cai W et al 2007 Nat. Photonics 1 224 [5] Ruan Z et al 2007 Phys. Rev. Lett. 99 113903 [6] Zolla F et al 2007 Opt. Lett. 32 1069 [7] Greenleaf A et al 2007 Opt. Express 15 12717 [8] Huang Y et al 2007 Opt. Express 15 11133 [9] Rahm M, Schurig D, Roberts D A, Cummer S A et al 2008 Photon. Nanostruct.: Fundam. Applic. 6 87 [10] Yao K, Li C and Li F 2008 Chin. Phys. Lett. 25 1657 [11] Kwon D H et al 2008 Appl. Phys. Lett. 92113502 [12] Kwon D H et al 2008 Appl. Phys. Lett. 92013505 [13] Yan W, Yan M et al 2008 New J. Phys. 10043040 [14] Li C and Li F 2008 Opt. Express 16 13414 [15] Nicolet A, Zolla F et al 2008 Opt. Lett. 331584 [16] Li C, Yao K, and Li F 2008 Opt. Express 1619366 [17] Ma H, Qu S B et al 2008 Opt. Express 1615449 [18] Zhang J J et al 2008 J. Opt. Soc. Am. B 251776
2009, Vol. 26 
