Investigation and Comparison of Light Propagation in Two Graded Photonic Crystal Structures
محورهای موضوعی : فصلنامه نانوساختارهای اپتوالکترونیکیAbdolrasoul Gharaati 1 , Nasrin Miri 2 , Zahra Zareian 3
1 - Physics Department, Payame Noor University, Tehran, Iran
2 - Physics Department, Payame Noor University, Tehran, Iran
3 - Physics Department, Payame Noor University, Tehran, Iran
کلید واژه: Photonic Crystals, graded index, effective refractive index, plane wave expansion,
چکیده مقاله :
In this paper, we study two different Graded Index (GRIN) photonic crystal (PC) structures which are named as structure type I and type II. The PC structures are made of the square rod in an air background. To design a GRIN PC structure the lattice constant has been altered in the direction transverse to propagation. We investigated focusing effect and waveguiding behavior of electromagnetic waves propagating throughout the GRIN structures. Wide incident beam with a Gaussian profile is illuminated to the both GRIN structures. In the case of structure type I, the incident wave bend toward the central part of the structure and after getting out of it focuses on the narrow area. The designed structure shows the strong focusing effect and increase normalized intensity and decreases the width of the outgoing wave. In the case of structure type II, the incoming beam after traveling short distance becomes distracted to the central part and remains confine in the middle of the structure. The exiting wave can be coupled to a photonic crystal waveguide. Plane wave expansion method has been used for analyzing dispersion relation. Propagation of electromagnetic wave within the graded structure has been simulated using finite-difference time-domain method
[1] E.Yablonovitch, Inhibited spontaneous emission in solid-state physics and electronics, Phys. Rev. Lett.,58(20) (1987) 2059.
[2] S. John, Strong localization of photons in certain disordered dielectric superlattices, Phys. Rev. Lett.,58(23) (1987) 2486.
[3] H. Kurt, M. Turduev, I. H. Giden, Crescent shaped dielectric periodic structure for light manipulation, Opt. Exp., vol.20, (2012)7184-7194.
[4] M. Turduev, I. H. Giden, H. Kurt, Extraordinary wavelength dependence of self-collimation effect in photonic crystal with low structural symmetry, Photonics and Nanostructures – Fundamentals and Applications, vol. 11(3)(2013)241–252.
[5] Ho. KM, CT.Chan,CM. Soukoulis, Existence of a photonic gap in periodic dielectric structures, Phys. Rev. Lett., 65(25) (1990)3152.
[6] M.Plihal,A.A. Maradudin, Photonic band structure of two-dimensional systems: The triangular lattice, Phys. Rev. Lett.,44(16) (1991)8565.
[7] K. Busch, S.John, Photonic band gap formation in certain self-organizing systems, Phys. Rev. Lett., 58(3) (Sep 1998)3896.
[8] K. Sakoda, Optical Properties of Photonic Crystals, Springer, 2001.
[9] K. M. Ho, C. T. Chan, C. M. Soukoulis, Existence of a photonic gap in periodic dielectric structures, Phys. Rev. Lett., 65(1990) 3152–3155.
[10] B. Igor A. Sukhoivanov, Igor V. Guryev, Photonic Crystals: Physics and Practical Modeling, Springer Series in Optical Sciences, Vol. 152, 2009.
