Reflectionless spatial beam benders with arbitrary bending angle by introducing optic-null medium into transformation optics* *Project supported by the National Natural Science Foundation of China (Grant Nos. 61971300, 11604292, 61905208, 11674239, and 11621101), the Scientific and Technological Innovation Programs (STIP) of Higher Education Institutions in Shanxi Province, China (Grant Nos. 2019L0159 and 2019L0146), and the Postdoctoral Science Foundation of China

Abstract

By introducing an optic-null medium into the finite embedded transformation, a reflectionless spatial beam bender is designed, which can steer the output beam by a fixed pre-designed angle β for an arbitrary incident angle. The bending angle β of the beam bender is determined by the geometrical angle of the device, which can be changed by simply choosing different geometrical angles. For various bending angles, the designed spatial beam bender can be realized by the same materials (i.e., an optic-null medium), which is a homogenous anisotropic material. Numerical simulations verify the reflectionless bending effect and rotated imaging ability of the proposed beam bender. A reduction model of the optic-null medium is studied, which can also be used for a reflectionless spatial beam bender with a pre-designed bending angle.