The Design of Large Curved Waveguide Based on Sunflower Graded Photonic Crystal

Abstract

In this paper, three large curved waveguides based on Sunflower Graded photonic crystal are designed. Numerical simulations of electromagnetic beam bending in Sunflower Graded photonic crystals have shown that homogenization based on the Maxwell–Garnett theory gives very good results for steering the electromagnetic field. In contrast to the progressive bending waveguide structures based on periodic photonic crystal designs reported in the literature, this structure is not only simple in design, but also the optical wave trends in the progressive bending waveguide structures are more smooth. Sunflower structures, due to their high circular symmetry, have a great advantage in making arbitrary curved waveguides. The results have some theoretical implications for the design of optical integrated circuits and the selection of optically thin communication devices. It is also useful for the selection of meta-materials.

Highly Efficient Terahertz Waveguide Using Two-Dimensional Tellurium Photonic Crystals with Complete Photonic Bandgaps

“…It is observed that there is a co-ownership operating frequency domain from the transmission efficiencies of TE and TM modes. A comparison of transmission efficiencies and insertion loss for the waveguides with different wavelengths between our results and the literature [18][19][20] is shown in Table 1 below. When the incident THz waves are incoming along the direction of the central axis of the PhCs waveguide, the power distributions of the THz signals in PhCs with different frequencies are shown as height expressions in Figure 7.…”

“…Wavelength Transmission Insertion Loss [18] 0.85, 1.31, 1.55 µm above 90 percent Less than 10 percent [19] 6 to 9.4 µm above 93.5 percent 0.029 dB/µm [20] 1.55 µm above 90 percent Less than 10 percent Our data 101.7 µm above 92.5 percent 0.34 dB When the incident THz waves are incoming along the direction of the central axis of the PhCs waveguide, the power distributions of the THz signals in PhCs with different frequencies are shown as height expressions in Figure 7. In Figure 7a,b, both TE and TM modes mostly diffuse out of the PhCs waveguide because of this frequency below the lower boundary of the complete PBG; thus, the PhCs waveguide loses the optical local effect at 2.850 THz.…”

“…Although the 5G millimeter transmission line has an ultrawide operating bandwidth from 23.45 to 31.25 GHz (relative bandwidth of 28.71%) only for TE mode, electromagnetic waves are allowed to transmit in the waveguide due to the Al 2 O 3 PhCs without PBGs for TM mode. Based on the extraordinary sunflower-graded PhCs, a large, curved waveguide has been envisaged [18]. A plasmonic waveguide has been designed by placing a graphene nanoribbon between two dielectric layers, which achieved a loss of 0.029 dB/µm and a coupling length of 187.9 µm [19].…”

Ultra-Wideband Terahertz Wave Absorber Using Vertically Structured IGIGIM Metasurface

“…In simulations, we divided the whole surface into small unit cells of side width of 1/8 the shortest wavelength of interest, then in the simulation we simulated the unit cell by using the periodic boundary condition in x-and y-directions, so that the computation time was greatly reduced. The graphene layers together with two small parts from their neighboring layers were treated as an effective layer with an effective refractive index [21], which simplifies the process, allowing for a coarser mesh resolution and reducing computational complexity. The effective refractive index can be calculated using the complex refractive index (CRI) model given by the following Equation (1) [22].…”

Asymmetrical Optical Response of Opal Photonic Crystals with Graded Thickness

“…[13][14][15] In this case, the thickness gradient is parallel to the growth direction that induces a graded refractive index contrast which shifts the position of the PBG. The value of such materials has been demonstrated in applications such as waveguides, 16,17 biosensors, 18 optical switches and filters, 19,20 along with templates for microporous and macroporous materials. 21 In these applications, the benefit of the thickness gradient is primarily in its consequence on the optical response, where the frequency of the photonic stopbands associated with the crystal is tuned based on thickness.…”