Wavelength-control of multi-narrowband high absorbers using symmetric and asymmetric photonic crystals with two MoS2-based defects

Abstract

Wavelength control of multi-narrowband absorbers plays a pivotal role in photonic devices. Such absorbers have been designed and constructed using highly absorbent layers. Ultra-thin layers of two-dimensional (2D) nanomaterials, such as MoS2, which are highly absorbent materials, have found attractive applications in photonics. In this study, defective photonic crystals (DPC) with two defects were formed by DMD with M and D indicating MoS2 and SiO2 layers, respectively. The calculation method used in this paper is the transfer matrix method (TMM). This paper proposes that symmetric and asymmetric DPCs with respect to each defect layer affect the number of defect modes, which ranges from one to four. Furthermore, changing the number of MoS2, defect positions, and thickness significantly impact the absorption, wavelength, and quality factor of the defect modes. In addition, changing the polarization and incident angle causes the wavelength of the defect modes to shift towards blue and changes the peak-to-peak distance. The distance between the defects provides wavelength adjustability, and the polarization and incident angle provide wavelength turnability. Moreover, changing the thickness of the D layer provides a redshift in the wavelength of the defect modes. The location of the defect layer, symmetry or asymmetry of DPCs affect the number and wavelength of defect modes. Increasing of distance between defects provides the same mechanism as a DPC with one defect. Also, photonic band gap does not depend on the thickness of the defect layer, the symmetry or asymmetry of the structure, periodicity of the top, middle, and bottom defect layer of DMD. This controllable design of multi-narrowband defect modes is likely to find numerous applications in multi-channel absorbers and sensors.