Wire Metamaterials-Based Microring Resonator

Wire Metamaterials-Based Microring ResonatorWire Metamaterials-Based Microring Resonator in Subwavelength StructureAhmed A. Ali, Mohanned J. and A. H. Al-JanabiAbstractIn this work we gratuity the possibility of building a subwavelength microring resonator by manipulating the unite cell in the wire metamaterials. The proposed structure consist of mesh of copper wires. Firstly one-dimensional waveguide, bended waveguide as well as beam splitter were investigated at microwave range (737 MHZ), accordingly the full structure of microring resonator were well-tried using commercial finite difference package CST Microwave.IntroductionNatural materials atomic number 18 made up by lots and lots of small elements like atoms and molecules. Some of these materials are amorphous, others are crystalline 1. Our main interest is in the interplay of waves and materials restricted to classical physics, the key parameter is a/, where a is the distance mingled with elements in the material and i s the free-space wavelength. Artificial materials in which atoms and molecules are replaced by macroscopic, man-made, elements 2. All dimensions are bigger than those in natural materials. When the separation between the elements is comparable with the wavelength then we have the Bragg effect 34, and when the separation is much smaller than the wavelength then we can resort to useful-medium theory 4. In the former case we have talked about photonic bandgap materials 5 and in the latter case about metamaterials 6.Generally, PCs are composed of periodic dielectric or metallo-dielectric na nary(prenominal)tructures that have alternating low and high dielectric constant materials (refractive index) in one, two, and three dimensions, which affect the propagation of electromagnetic waves inside the structure 7. Due to this periodicity, PCs exhibit a unique optical property, namely, a photonic band gap (PBG) where electromagnetic mode propagation is absolutely zero due to reflection. PBG is the range of frequencies that neither absorbs light nor allows light propagation. By introducing a defect (point or line or both) in these structures, the periodicity and thus the completeness of the band gap are broken and the propagation of light can be localized in the PBG region. Such an sequel allows realization of a wide variety of active and passive devices for signal processing such as, add-drop filters, power splitters, multiplexers and demultiplexers, triplexers, switches, directional couplers, bandstop filters, bandpass filters, and waveguides.However, because of their wavelength-scale period, PCs result in large devices. This hard restrains the range of applications, specifically in the low-frequency regimes where the wavelength is large. Metamaterials, on the contrary, possess spatial scales typically much smaller than the wavelength1Since they were theoretically proposed by Pendry et al 8, and experimentally demonstrated by Smith et al.9, metamaterials have attrac ted intensive research interest from microwave engineers and physicists in recent years because of their wide applications in super-lenses 6, 10, slow light 11, 12, optical faulting 13, and wave guiding 14, 15Metamaterials are usually studied under the approach of the effective medium theory and experimentally measured from the far airfield 4. They are mainly considered for their macroscopic properties owing to the subwavelength nature of their unit cells.Recently, Fabrice Lemoult et al 16 have merged the wave guiding possibilities offered by PCs and the kabbalistic subwavelength nature of metamaterials by pore on the propagation of waves in metamaterials made of resonant unit cells that are arranged on a deep subwavelength scale to go beyond the effective medium approximation. By manipulating the unit cell of the wire they were able to experimentally investigate the main components that can be used to control waves at the deep subwavelength scale a cavity, a linear waveguide, b ending as well as the beam splitterHere we were be able to model their trunk first using the CST Microwave studio. Then we would expand the work to make a ring resonator used as add-drop filter or to built the field up to gain the nonlinear effect.Firstly the frequency response for the system were measured for a mesh of 20*20 Copper wires with 0.3cm diam and 1.2cm separation 40cm (a) and length by measuring the S21 between two discrete ports position on the opposite side of the system, as shown in the system mannikin figure (1), then the result were compared with the same structure but with 37cm length as shown in figure (2).figure (1) structure for the system under consideration, 20*20 Copper wiresFigure (2) S21 for the both wire lengths with the frequency selective lineThe scanned bandwidth was about 300MHz from (600-900) MHz, then a certain frequency (737MHz) were selected on which the shortstop wires (37cm) would have maximum transmission and the foresighteder ones (40cm) wires would have the lower transmission (band gap region slightly above the resonance frequency of fn=nC/2L, were n an integer C speed of light, Lwire length). Linear waveguide were investigated by shorting a single raw of wires (37cm) inside the 20*20 mesh of (40cm) wires and arranging the field propagation on the waveguide as shown in figure (3), profile of the signal inside the waveguide illustrated in the inset give the waveguide width of /32Figure (3) subwavelength waveguide by shorting one row of the wiresIt clearly shows the weak propagation on the system due to weak handicap between our unit cell, wires here,. Anyhow the counter plot for the waveguide, shown in figure (4), clearly shows the resonance around the short wires and forbidden propagation around long ones.Figure (4) subwavelength waveguide by shorting one row of the wires (contour view)To enhance the coupling between the unit cells (wires here) and increase the waveguide efficiency two adjacent rows of wires wer e shortened. The field map for the latter case were presented in figure (5).Figure (5) subwavelength waveguide by shorting two rows of the wires (showing good coupling)Bended waveguide and beam splitter were simulate also as shown in figures (6 and 7) respectively.Figure (6) subwavelength bended waveguideFigure (7) subwavelength beam splitterFinally, the complicated structure of microring resonator were molded as shown in figure (8)Figure (8) subwavelength ring resonatorReferences1N. D. Ashcroft, NeilW. and Mermin, Solid state physics, First. Orlando, FL Saunders College Publishing, 1976.2D. Smith, W. Padilla, D. Vier, S. Nemat-Nasser, and S. Schultz, Composite medium with simultaneously negative permeability and permittivity, Phys. Rev. Lett., vol. 84, no. 18, pp. 41847, May 2000.3C. J. Humphreys, The significance of Braggs law in electron diffraction and microscopy, and Braggs second law., Acta Crystallogr. A., vol. 69, no. Pt 1, pp. 4550, Jan. 2013.4B. A. Slovick, Z. G. Yu, and S. 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