Extremely high contrast asymmetric transmission with linear tunability in chiral metamaterials

In this paper, asymmetric transmission with extremely high contrast for linear polarization is proposed in chiral split ring resonators. Results show that only specific cross-polarization can pass through the structure with a high power transmission efficiency of 0.9 (amplitude transmission 0.95), which is much higher than those reported before in infrared region. The contrast between the two cross-polarizations is also very large (larger than 24.5 dB). Another merit of our scheme is that the operation wavelength is broadband, and can shift linearly to achieve asymmetric transmission over a range of 330 nm by the tuning of a single structural parameter. These excellent features of asymmetric transmission make our scheme very promising in practical applications, such as integrated optical diodes.