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Dependence of the (a) Reflectance R, (b) reflected phase ϕ r , and (c) reflected group delay τ r on frequency for different air gap thicknesses. Here =
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In this paper, we have shown that tunable nonlinear group delay of reflected light beam at terahertz frequencies can be achieved by a modified Otto configuration with the insertion of monolayer graphene and nonlinear substrate. This large nonlinear reflected group delay originates from the excitation of surface plasmon resonance at the interface of...
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In this paper, a simple terahertz (THz) leaky-wave antenna (LWA) composed of periodic gapped graphene ribbons and a silicon substrate is presented. The graphene sheets of the antenna operate in an electric field with a resonance distribution of transverse electric (TE) surface plasmon polaritons (SPPs). The THz LWA has both negative and positive pr...
Citations
... Therefore, the threshold of optical bistability can be intensively reduced [7][8][9][10]. In addition to Fabry-Perot resonances and Tamm plasmon polaritons, there are various mechanisms that can reduce the threshold of optical bistability, such as surface plasmon polaritons [15][16][17], topological edge states [18,19], and Fano resonances [20]. ...
In this paper, we investigate the low-threshold optical bistable absorption in an asymmetrical one-dimensional photonic crystal structure (1D-PhC) containing a Weyl semimetal (WSM) defect layer. Dirven by the strong third-order nonlinear effect of the WSM and the field enhancement of the defect mode, low-threshold bistable absorption is achieved in the terahertz band. After optimizing the parameters, the rising threshold intensity is 83.7817 MW/m2 and the falling threshold intensity is 49.39 MW/m2, which are lower than the threshold intensities of bistable absorption in the reported works. Meanwhile, we discuss the effects of Fermi level of WSM, incident angle, and the numbers of periods of the left and right 1D-PhCs on the bistable absorption. Our work would facilitate the design of high-performance all-optical switches, all-optical logics, and optical absorbers.
Low-threshold bistable absorption in asymmetrical one-dimensional photonic crystals containing Weyl semimetal defects with rising threshold intensity Iup = 83.7817 MW/m2 and falling threshold intensity Idown = 49.39 MW/m2
... [22] Xu et al. studied the tunable bistable reflected group delay based on a modified Otto configuration with the insertion of monolayer graphene and a nonlinear substrate. [23] It is not difficult to see that the enhancement and regulation approach to group delay based on 2D materials will be a feasible direction to realize practical delay devices, and this still represents the direction of study of optical delay, with large group delay, easier adjustment and a simple structure. ...
In this paper, the reflected group delay from a multilayer structure where bulk Dirac semimetals (BDS) is coated on one-dimensional photonic crystal (1D PC) separated by a spacer layer is investigated theoretically. It is shown that the group delay of reflected beam in this structure can be significant enhanced negatively and can be switched from negative to positive. The enhanced group delay originates from the steep phase change caused by the excitation of optical Tamm state (OTS) at the interface between the BDS and spacer layer. Moreover, the positive and negative group delay can be actively tuned through the Fermi energy and the relaxation time of the BDS. We believe that this enhanced and tunable delay scheme has important research significance for fabrication of optical delay devices.
... Taking the representative graphene in two-dimensional materials as an example, it has obvious advantages in realizing enhanced delay phenomenon due to its excellent photoelectric characteristics [14,15]. Researchers have studied many ways to enhance and regulate the reflected group delay of optical pulse in graphene [17]. It is not difficult to see that the group delay of micro-nano structure' s enhancement and regulation approach based on two-dimensional materials will be one of the feasible directions to realize practical delay devices. ...
In this paper, the reflected group delay from a multilayer structure where Dirac semimetal is coated on one-dimensional photonic crystal (1D PC) separated by a spacer layer is investigated theoretically. It is shown that the group delayof reflected beam in this structure can be significant enhanced negatively and can be switched from negative to positive. The enhanced group delay originates from the steep phase change caused by the excitation of Tamm plasmons at the interface between the Dirac semimetal and spacer layer. It is clear that the positive and negative group delay can be actively tuned through the Fermi energy and the relaxation time of the Dirac semimetal. We believe this enhanced and tunable delay scheme is promising for fabricating optical delay devices and other applications at middle infrared band.
