WITHDRAWN: Perfect asymmetric transmission for linear polarization in background reflection-free bilayer dielectric metasurfaces

Abstract

In spite of the importance of asymmetric transmission (AT) with near-unity value and significantly high contrast of transmission, such a perfect AT has not yet been realized in reciprocal systems. For single resonance, it is already known that the upper limit of AT is identical to the background amplitude reflection coefficient. Nevertheless, if multiple resonances simultaneously contribute to AT, their coherent coupling enables us to obtain perfect AT, even when background reflection completely vanishes. Taking bilayer dielectric metasurfaces composed of orthogonal silicon nanorods embedded in silica glass as examples, here we show that perfect AT can be realized for linear polarization with characteristics comparable with bulky optical isolators based on Faraday effect: AT of 0.9994 with dramatically high contrast 35.1dB at telecom wavelength, the spectral position of which is tunable by properly changing the structural parameters. The analytical model based on the quasinormal-mode expansion well agrees with numerical results, revealing the concurrent contributions of multiple resonances. The presented perfect AT has the advantages of excellent performances of AT and compact structures without bulky devices for field bias or temporal modulations, enabling practical applications for optical computing, high-contrast polarization multiplexing and conversion.