title: Unidirectional transmission realized by two nonparallel gratings made of isotropic media.
abstract: We realize a unidirectional transmission by cascading two nonparallel gratings (NPGs) made of isotropic, lossless, and linear media. For a pair of orthogonal linear polarizations, one of the gratings is designed as a polarizer, which is a reflector for one polarization and a transmitter for the other; another grating is designed as a polarization converter, which converts most of one polarized incident wave into another polarized transmitted wave. It is demonstrated by numerical calculation that more than 85% of the incident light energy can be transmitted with less than 1% transmission in the opposite direction for linearly polarized light at normal incidence, and the relative bandwidth of the unidirectional transmission is nearly 9%. The maximum transmission contrast ratio between the two directions is 62 dB. Unlike one-way diffraction grating, the transmitted light of the NPGs is collinear with the incident light, but their polarizations are orthogonal.
authors.affiliation: College of Optoelectics Science and Engineering, National University of Defense Technology, Changsha, 410073, China. wmye72@126.com
authors.forename: Wei-Min
authors.initials: WM
authors.lastname: Ye
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Yuan
authors.forename: Chun
authors.initials: C
authors.lastname: Zeng