Tunable and asymmetric transmission of light in visible spectrum

Abstract

In modern optic and photonic applications, tunability of the asymmetric transmission has become important due to its adjustable unidirectional transmission. In this study, we design a three-dimensional trapezoidal metallic nano structure on a stretchable substrate. It shows broadband tunable asymmetric light transmission in the visible spectrum. The proposed structure is made of a periodic nano array of a trapezoidal shaped aluminum on a stretchable substrate. The transmission properties of the proposed structure with respect to the geometric parameters were systematically investigated employing finite-difference time-domain computations. It was shown that the intensity and the bandwidth of the asymmetric light transmission between 400 nm and 800 nm wavelengths change when the flexible substrate is stretched. The period of the designed structure varies depending on the stretch of the substrate. For example, when the substrate is stretched, the period of the structure is 450 nm and when it is unstretched, the period is 350 nm. This increase in the period causes a red shift in the wavelength range of the asymmetric transmission. While the asymmetric transmission under unstretched case starts at 350 nm and stops at 514.5 nm, under stretched case it starts at 450 nm and stops at 661.5 nm. In addition, the performance of our structure is insensitive the polarization of the incoming radiation in both forward and backward illumination directions. This study provides a path toward the realization of tunable optical devices for the applications which require dynamic tunability. © 2019 SPIE.