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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. [ABSTRACT FROM AUTHOR]

Among ultrathin transition metal dichalcogenides, WS2 monolayers with a direct bandgap have attracted intensive attention because of their narrow optical absorption centered at 619 nm. However, these layers with stronger absorption are needed in applications such as photonic devices. In this paper, an increase in absorption is achieved through plasmonic coupling of a nearby Au thin layer directly or through a spacer to the WS2 monolayer. The optical properties of the designed structures are investigated by the transfer matrix method in the visible wavelength region. In the structure consisting of a WS2 monolayer with Au and spacer layers, the absorption at 619 nm was increased to 61%. Sharp optical absorption as high as 40% for a large range of incidence angles in both polarizations was retained. Our study provides useful information for the design of WS2 monolayers in photonic devices for practical applications. [ABSTRACT FROM AUTHOR]

Investigation of optical absorption of monolayer Molybdenum disulfide, MoS 2 , has attracted intense attention for its application in the visible optoelectronic and photonic elements. In this paper, one-dimensional photonic crystals (1DPCs) including MoS 2 monolayer are designed toward increasing the optical absorption. Reflection and absorption spectra for TE and TM modes are calculated by transfer matrix method (TMM) for different designs. We found that the optical absorption wavelength of designed structures can be tuned by changing the number of period or using of different materials in the 1DPC. [ABSTRACT FROM AUTHOR]

Because of their desirable optical absorption responses, two-dimensional transition metal dichalcogenides have potential applications in optoelectronic devices. However, whether optoelectronic devices based on these materials are capable of absorbing light in a wide optical range is debatable. In this paper, we suggest using Thue–Morse quasi-photonic crystals based on Si 3 N 4 , SiO 2 layers and transition metal dichalcogenides monolayers for optoelectronic devices. Absorption was calculated on the basis of the transfer matrix method. Optical absorption as large as 90% in a broadband wavelength range was achieved for both transverse-electric and transverse-magnetic polarizations. Our results can be useful for designing photonic devices and perfect absorbers with high absorption efficiencies. • Using two-dimensional materials transition metal dichalcogenides (TMDCs) with direct bandgaps. • Thue–Morse Quasi-Photonic Crystals (TQPC) can reach ultra-broadband perfect absorption in optical ranges, which is promising for the development of photovoltaic and optoelectronic devices. • S 2 -TQPC in structure I using MoS 2 and MoSe 2 monolayers, when B = mb and N = 10, was shown that the absorption reaches up to 90% in the 400–675 nm range. [ABSTRACT FROM AUTHOR]