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Meta 2010 & FEM 2010 – Rome, 13-15 December 2010 Effect of Localized States on Photonic Quasicrystal Waveguides Emiliano Di Gennaro (1) , Priya Rose T. (1) , Gianluigi Zito (2) , Giancarlo Abbate (1) , and Antonello Andreone (1) (1) CNR-SPIN and University of Naples “Federico II,” Department of Physics Naples, Italy – E-mail: emiliano@na.infn.it, priyarose@na.infn.it, abbate@na.infn.it, andreone@unina.it (2) CNR-ICIB “E. Caianiello”, Pozzuoli (NA), Italy – E-mail: zito.gianluigi@libero.it In recent years, photonic quasicrystals have attracted enormous interest in the field of photonics of complex structured materials. The lack of translational symmetry into quasiperiodic and aperiodic crystals is compensated by longrange quasiperiodic translational order and high rotational symmetries not achievable by conventional periodic crystals. Photonic Quasicrystals (PQCs) may possess large photonic bandgaps (PBGs) [1,2] with very interesting properties of light transmission, wave guiding and localization [3] that can be exploited in a wide variety of electro-optical and photonic applications. In this work we study the PBG properties of an octagonal interferential PQC. The 2D quasiperiodic pattern is obtained by placing ideal dielectric cylinders (infinitely long) where the interference of 8 coherent light beams shows its local maxima [4]. In order to characterize the in-plane PBG properties of the abovementioned structure, we have designed and performed a series of experiments in the microwave regime (8-20 GHz). The sample under study consists of alumina cylindrical rods in air inserted in a parallel plate waveguide. Transmittance and field maps are obtained using an x-y robot and two dipole antennas connected to a two-port vectorial network analyzer (VNA) HP 8720C [5]. We focus on the response of a linear waveguide, whose transmittance can be controlled by tuning the dielectric properties of the central post. Experimental results are compared and found in very good agreement with numerical simulations obtained by finite differences timedomain technique. References [1] M.E. Zoorob , M.D.B. Charlton, G.J. Parker, J.J. Baumberg, M.C. Netti, “Complete photonic bandgaps in twelve-fold symmetric quasicrystals” Nature 404, 740, 2000 [2] Y. S. Chan, C. T. Chan, and Z. Y. Liu, “Photonic Band Gaps in Two Dimensional Photonic Quasicrystals” , Phys. Rev. Lett. 80, 956, 1998 [3] S. S. M. Cheng, L. Li, C. T. Chan, and Z. Q. Zhang, "Defect and transmission properties of two-dimensional quasiperiodic photonic band-gap systems," Phys. Rev. B 59, 4091, 1999 [4] G. Zito, B. Piccirillo, E. Santamato, A. Marino, V. Tkachenko, and G. Abbate, "Twodimensional photonic quasicrystals by single beam computer-generated holography," Opt. Express 16, 5164, 2008 [5] E. Di Gennaro, C. Miletto, S. Savo, A. Andreone, D. Morello, V. Galdi, G. Castaldi, and V. Pierro, “Evidence of local effects in anomalous refraction and focusing properties of dodecagonal photonic quasicrystals,” Phys. Rev. B 77, 193104, 2008 22
Meta 2010 & FEM 2010 – Rome, 13-15 December 2010 Scattering Properties of Carbon Nanotube Arrays A. G. Chiariello (1) , C. Forestiere (2) , A. Maffucci (1) and G. Miano (2) (1) University of Cassino, Department DAEIMI, via Di Biasio 43, Cassino, 03043, Italy Email: chiariello@unicas.it, maffucci@unicas.it (2) University of Naples Federico II, Department of Electrical Engineering, via Claudio 21, Naples, 80125, Italy E-mail: carlo.forestiere@unina.it, miano@unina.it Due to their unique electrical, thermal and mechanical properties, carbon nanotubes (CNTs) have been proposed for a wide range of nano-electronics applications [1], including interconnects, packages, transistors, passive devices, antennas [2]. Recently, carbon nanotubes have been also proposed as innovative scattering material [3-4], in the realization of absorbing materials in the aircraft industry, in view of replacing conventional materials, like polymeric sheets filled with magnetic or dielectric loss materials, such as ferrite, permalloy. In this work we investigate the scattering properties of an array of finite-length single-wall carbon nanotubes (SWCNTs), up to terahertz frequencies. The problem is cast in terms of a Pocklington-like equation. The current density along the CNT is described by a quasi-classical transport model, recently proposed. The numerical solution is obtained by means of the Galerkin method. Case studies are carried out, either referred to isolated SWCNTs and array of SWCNTs, aimed at investigating the frequency behaviour of the scattered field. a) b) Figure 1 – (a) Scattered electric field for a 20µm-long CNT, with radius of 2.72nm at 300K, illuminated by a TEM plane wave impinging orthogonally. The scattered field has been evaluated at a distance of 100 μm (b) Spatial distributions of the current along the CNT at the frequencies References [1] R. H. Baughman, A.A. Zakhidov, W.A. de Heer., “Carbon nanotubes--the route toward applications ,” Science, 297(5582), 787-792, 2002 [2] S. A Maksimenko, G. Ya. Slepyan, A. M. Nemilentsau, and M. V. Shuba, “Carbon nanotube antenna: Far-field, near-field and thermal-noise properties,” Physical Rev. E, 40, 2360, 2008. [3] J. Hao and G.W. Hanson, “Electromagnetic scattering from finite-length metallic carbon nanotubes in the lower IR bands”, Physical Review B, 74, 035119, 2006. [4] A.G. Chiariello, C. Forestiere, A. Maffucci and G. Miano, “Scattering Properties of Carbon Nanotube Arrays,” in press on Intern. Journal of Microwave and Wireless Technologies 23
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Abstracts - Dipartimento di Elettronica Applicata

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