The adjustable and tunable narrowband optical absorber by insertion of the WSe2 and WS2 monolayer in symmetric and asymmetric defective photonic crystals

Abstract

Narrowband optical absorption plays a key role in photonic sensors and photovoltaic elements. Here, we propose a design of creating narrowband absorbers based on the symmetric and asymmetric defective photonic crystals (SDPCs and ADPCs) consisting of defects in the form of DMD in which M indicates the WS2 or WSe2 monolayer and D represents the SiO2 layer. In this paper, the effect of the defect layer thickness, polarization, and incident angle of light on the number and wavelength of defect modes in both symmetric and asymmetric structures is investigated. The findings suggest that the wavelength of the defect modes can be adjusted by varying the thickness of layer D as well as the design of the wavelength and tuned by polarization and incident angle of light. In both SDPC and ADPC, the wavelength of the defect mode shows red shift with an increase in the thickness of layer D and exhibits blue shift with an increase in the angle of light in both TE and TM polarization. This narrowband absorber demonstrates great potential for being adopted in the detection of photodetectors, absorbent filters, and the like.

Data analysis on the three defect wavelengths of a MoS2-based defective photonic crystal using machine learning

“…The second defect mode is located at 621 nm, in the middle of the PBG, which changing any parameters, p , q , r , or t , will not affect its wavelength. In symmetric DPC structures with one defect, a single defect mode with minimum wavelength changes concerning the structural parameters is located in the middle of the PBG, near the design wavelength 52 . By increasing the number of defects with the condition that all of them are symmetrical, the defect mode located in the middle of PBG remains constant and other modes are added around it.…”

“…Figure 3 b shows that, while, for q values less than 10 three different defect modes can be recognized, increasing q to the values greater than 10 reduces the defect modes to one. This phenomenon occurs as the incoming light can’t reach the second defect of the structure and behaves like a DPC with one symmetric defect 52 . Such a happening with r values greater than 10 can be also deduced from Fig.…”