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In the present study, we have explored the absorption properties of a monolayer graphene-based photonic heterostructure, which consists of topological photonic configurations, graphene, and a Bragg mirror. The optical attributes were computed by using the 4 × 4 transfer matrix method. The results indicate that the creation of topological interface states and strong coupling between these resonant modes result in mode splitting, leading to the formation of hybrid modes known as coupled topological interface states with unity transmittance. The number of absorption modes can be modulated with an appropriate selection of cascaded photonic structures. Our proposed design with 1, 3, 5, and 7 cascaded topological photonic structures provides 1, 5, 9, and 13 absorption modes with greater than 90 % absorption. The findings also reveal that absorption peak strength is greatly influenced by Fermi-level and magnetic fields; switching of the modes from absorption to reflection and vice versa is achieved by suitable electrical and magnetic biasing. Our proposed design offers various applications, such as switchable filters, absorbers, and modulators. [ABSTRACT FROM AUTHOR]

In this work, the narrowband and broadband absorption characteristics of single layer graphene-based photonic structures are investigated. The optical features were determined utilizing the 4 × 4 transfer matrix method. The results indicate that the proposed design incorporating monolayer graphene achieves absorption rates exceeding 90% across a bandwidth of 1.8 THz. Additionally, the suggested photonic configuration has the potential to function as a triple-mode narrowband absorber through the alteration of layer positioning or the substitution of materials. The numerical relationships between the refractive indexes of materials A, B, and C have been formulated to facilitate broadband and narrowband absorption. The absorption characteristics of the proposed design have been significantly influenced by the Fermi-level of Graphene and the magnetic field. The results indicate that the absorption value of both broadband and narrowband absorbers can be dynamically adjusted by manipulating the Fermi-level of Graphene and magnetic field. The photonic configuration being proposed presents novel opportunities for the development of electrically and magnetically tunable narrowband and broadband absorbers. • The proposed design can offer both broadband and multi-mode narrowband absorption. • The triple-mode narrowband absorption with a value greater than 95% achieved. • The proposed novel design provided broadband absorption over a bandwidth of 1.8 THz. • Formulated numerical relations for broadband and multi-mode absorption. • The design enables dynamic absorption tuning via electrical and magnetic biassing. [ABSTRACT FROM AUTHOR]

In the current study, we have explored the broadband absorption characteristics of graphene-layered random photonic crystals by the 4 × 4 characteristic matrix method. The findings confirm that under the influence of magnetic field B, optimal semi-random photonic crystals are capable of providing broadband absorption with a value greater than 84% in the wavelength range of 74.8–85.57 μm. The absorption band is tuned to desired frequencies by appropriate selection of the thickness of the silicon carbide layer. An absorption and FWHM enhancement with respect to the number of layers in each elementary unit, Fermi-level, and period number are numarically revealed. The application of a positive magnetic field minimises fluctuations and enhances the FWHM value in the desired absorption band for LCP waves, whereas the converse is true for RCP waves. The proposed absorber has applications in polarization selective absorbers, sensors and terahertz imaging. • A broadband Terahertz absorber designed with only a minimal number of graphene layers. • An absorption band is tuned to the desired frequencies by the appropriate selection thickness of the spacer layer. • The random structures have more potential to provide broadband absorption compared to periodic structures. • The anisotropic property of graphene plays a crucial role in reducing fluctuations in a selected absorption band. [ABSTRACT FROM AUTHOR]