In this paper, we have theoretically investigated the absorption response in a monolayer MoS2 covered one-dimensional dielectric grating structure at visible region. Through RCWA calculation, a dual-band total optical absorption has been numerically obtained in this proposed resonance structure. It has been demonstrated that the dual-band total absorption is enabled by the guided resonances with the critical coupling. Moreover, our calculation results also show that the resonance absorption wavelength could be controlled by choosing the proper structural parameters of this system. The ultra-high dual-channel light absorption offered by this simple and compact geometry may lead to the multiple-channel photonic devices in applications of optical detecting, sensing, storage and communication.
An asymmetric transmission device has been presented to realize high-performance one-way transmission at visible frequencies. This device consists of a pair of non-symmetric pyramid-shaped silicon gratings separated by a metal/dielectric multilayer structure (MDMS). Simulation results demonstrates that, compared with conventional Cr grating, MDMS with pyramid-shaped silicon gratings will greatly enhance the coupling and decoupling between the propagating waves in free space and the high frequency modes in MDMS, rendering an improved oneway transmission performance. The improved one-way transmission performance offered by our design may hold great potential in designing the optical isolator and polarizer for ultra-compact photonic integrated circuit.