Giant Broadband One Way Transmission Based on Directional Mie Scattering and Asymmetric Grating Diffraction Effects

High performance optical diode-like devices are highly desired in future practical nano-photonic devices with strong directional selectivity. We demonstrate a kind of giant broadband reciprocity optical diode-like devices by simultaneously using the directional Mie scattering effect and the asymmetric grating diffraction effect. The maximum asymmetric subtraction and the asymmetric transmission ratio can reach nearly 100% and 40 dB at specified wavelength, respectively. In a wide waveband from 500 nm to 800 nm, the asymmetric subtraction and the ratio keep larger than 80% and 3.5 dB, respectively, even under oblique incidence. To the best of our knowledge, this is the best one-way-transmission effect observed in the reciprocity optical diode-like devices. In addition, we further demonstrate that this one-way-transmission effect can bring an effective absorption enhancement on gold films. The giant, broadband and angle-insensitive one-way-transmission effect demonstrated here is far beyond the well-known anti-reflection effect in the light-trapping devices and will bring new design philosophy for nano-photonic devices.