Search for: plane-wave-expansion
0.009 seconds

    Analyzing symmetry in photonic band structure of gyro-magnetic photonic crystals

    , Article Proceedings of SPIE - The International Society for Optical Engineering ; Volume 8096 , 2011 ; 0277786X (ISSN) ; 9780819487063 (ISBN) Najafi, A ; Khorasani, S ; Gholami, F ; Sharif University of Technology
    In the band structure analysis of photonic crystals it is normally assumed that the full photonic gaps could be found by scanning high-symmetry paths along the edges of Irreducible Brillouin Zones (IBZ). We have recently shown [1] that this assumption is wrong in general for sufficiently symmetry breaking geometries, so that the IBZ is exactly half of the complete BZ. That minimal required symmetry arises from the requirement on time-reversal symmetry. In this paper we show that even that requirement might be broken by using gyro-magnetic materials in the composition of photonic structures we can observe that the IBZ extends fully to the boundaries of the complete BZ, that is IBZ must be as... 

    Efficient analysis of confined guided modes in phoxonic crystal slabs

    , Article Journal of Lightwave Technology ; Volume 35, Issue 17 , 2017 , Pages 3734-3742 ; 07338724 (ISSN) Aram, M. H ; Khorasani, S ; Sharif University of Technology
    Today's standard fabrication processes are just capable of manufacturing slab of photonic and phononic crystals, so an efficient method for analysis of these crystals is indispensable. Plane wave expansion (PWE) as a widely used method in studying photonic and phononic (phoxonic) crystals in full three dimensions is not suitable for slab analysis in its standard form, because of convergence and stability issues. Here, we propose a modification to this method which overcomes these limitations. This improved method can be utilized for calculation of both photonic and phononic modes in phoxonic slabs. While in the standard three-dimensional PWE, Fourier series are used to estimate the field... 

    Construction of Dirac points using triangular supercrystals

    , Article Applied Physics A: Materials Science and Processing ; Volume 115, Issue 2 , May , 2014 , Pages 581-587 ; ISSN: 09478396 Aram, M. H ; Mohajeri, R ; Khorasani, S ; Sharif University of Technology
    We show a methodology for how to construct Dirac points that occur at the corners of Brillouin zone as the Photonic counterparts of graphene. We use a triangular lattice with circular holes on a silicon substrate to create a Coupled Photonic Crystal Resonator Array (CPCRA) which its cavity resonators play the role of carbon atoms in graphene. At first we draw the band structure of our CPCRA using the tight-binding method. For this purpose we first designed a cavity which its resonant frequency is approximately at the middle of the first H-polarization band gap of the basis triangular lattice. Then we obtained dipole modes and magnetic field distribution of this cavity using the Finite... 

    Modal transmission-line theory of optical waveguides

    , Article Journal of Electromagnetic Waves and Applications ; Volume 19, Issue 7 , 2005 , Pages 891-906 ; 09205071 (ISSN) Dabirian, A ; Akbari, M ; Sharif University of Technology
    In this paper, we describe a vectorial and analytical technique, based on modal transmission-line theory, for solving guided modes of arbitrary shaped cylindrical optical waveguides. The waveguide materials can be either transparent or absorbing. In this technique, mode solving is approached by periodic repetition of the waveguide and using modal transmission-line theory. Pertinent information about guided modes of the waveguide is extracted from transmission-line features. Two examples illustrate the utilization of this technique for analysis of optical waveguides  

    A novel method for band structure analysis of photonic crystal slabs

    , Article IEEE Photonics Journal ; Volume 3, Issue 6 , 2011 , Pages 1111-1122 ; 19430655 (ISSN) Nekuee, S. A. H ; Akbari, M ; Mehrany, K ; Sharif University of Technology
    We propose a new method to extract the modes of photonic crystal slabs and, thus, obtain their band structures. These slabs, which are 2-D periodic structures with finite thickness, can completely confine light and have the important advantage of simple construction for applications in integrated optic devices. In this paper, reflection pole method (RPM) is utilized to analyze photonic crystal slabs. Modes are poles of reflection and transmission coefficients of multilayered structures. According to this principle, modes can be detected by only pursuing phase variations of transmission coefficients that are equal to π rad. Therefore, extraction of modes becomes fast and simple through... 

    Influence of asymmetry on the band structure of photonic crystals

    , Article Proceedings of SPIE - The International Society for Optical Engineering, 26 January 2010 through 28 January 2010 ; Volume 7609 , January , 2010 ; 0277786X (ISSN) ; 9780819480057 (ISBN) Moosavi Mehr, S. H ; Khorasani, S ; Sharif University of Technology
    Computer calculation of photonic band structure for unit cells of various symmetry in the two-dimensional square lattice suggests that the bandgap calculated by traversing the ΓXM triangle in k-space is only reliable when the unit cell is C4v symmetric. For structures of lower symmetry, examining a two-dimensional subset of the first Brillouin zone will give smaller bandgaps