Adjustable defect modes in symmetric and asymmetric two-dimensional defective photonic crystal based on MoSe2

MoSe2 two-dimensional nanostructure is a suitable candidate for optoelectronic applications due to its unique properties such as high absorption and direct band gap. One way to increase the absorption in such a monolayer is to place it as a defect in one-dimensional photonic crystal (PC). The location of defect in the PC can form either symmetrical or asymmetric PC, which affects the number and frequency of defect modes. In this paper, in order to achieve high absorption and adjustability of the defect mode wavelength, the effect of defect layer thickness, PC layers thickness, and periodicity are investigated in both symmetric and asymmetric PCs. In the optimal design, we have achieved a perfect absorption in the asymmetric structures with one defect mode in the middle photonic band gap and in asymmetric PCs with two defect modes the absorption was found to be 70%~80% On both sides photonic band gap. By changing the thickness of the defect layer and the wavelength of the design, the wavelength of the defect mode can be adjusted, which is useful for application in detectors and absorbent filters.