567 research outputs found

    Theoretical investigation of one-dimensional cavities in two-dimensional photonic crystals

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    We study numerically the features of the resonant peak of one-dimensional (1-D) dielectric cavities in a two-dimensional (2-D) hexagonal lattice. We use both the transfer matrix method and the finite difference time-domain (FDTD) method to calculate the transmission coefficient. We compare the two methods and discuss their results for the transmission and quality factor Q of the resonant peak. We also examine the dependence of Q on absorption and losses, the thickness of the sample and the lateral width of the cavity. The Q- factor dependence on the width of the source in the FDTD calculations is also given.Comment: 25 pages, 8 figure

    Metal-insulator transitions in anisotropic 2d systems

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    Several phenomena related to the critical behaviour of non-interacting electrons in a disordered 2d tight-binding system with a magnetic field are studied. Localization lengths, critical exponents and density of states are computed using transfer matrix techniques. Scaling functions of isotropic systems are recovered once the dimension of the system in each direction is chosen proportional to the localization length. It is also found that the critical point is independent of the propagation direction, and that the critical exponents for the localization length for both propagating directions are equal to that of the isotropic system (approximately 7/3). We also calculate the critical value of the scaling function for both the isotropic and the anisotropic system. It is found that the isotropic value equals the geometric mean of the two anisotropic values. Detailed numerical studies of the density of states for the isotropic system reveals that for an appreciable amount of disorder the critical energy is off the band center.Comment: 6 pages RevTeX, 6 figures included, submitted to Physical Review

    Two-dimensional photonic crystal polarizer

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    A novel polarizer made from two-dimensional photonic bandgap materials was demonstrated theoretically. This polarizer is fundamentally different from the conventinal ones. It can function in a wide frequency range with high performance and the size can be made very compact, which renders it useful as a micropolarizer in microoptics.Comment: 8 pages, RevTex, 4 figure

    Spontaneous emission in the near-field of 2D photonic crystals

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    We show theoretically that photonic crystal membranes cause large variations in the spontaneous emission rate of dipole emitters, not only inside but also in the near-field above the membranes. Our three-dimensional finite difference time-domain calculations reveal an inhibition of more than five times and an enhancement of more than ten times for the spontaneous emission rate of emitters with select dipole orientations and frequencies. Furthermore we demonstrate theoretically, the potential of a nanoscopic emitter attached to the end of a glass fiber tip as a local probe for mapping the large spatial variations of the photonic crystal local radiative density of states. This arrangement is promising for on-command modification of the coupling between an emitter and the photonic crystal in quantum optical experiments.Comment: 3 pages, 3 figures. Figure 2 colo

    Electric coupling to the magnetic resonance of split ring resonators

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    We study both theoretically and experimentally the transmission properties of a lattice of split ring resonators (SRRs) for different electromagnetic (EM) field polarizations and propagation directions. We find unexpectedly that the incident electric field E couples to the magnetic resonance of the SRR when the EM waves propagate perpendicular to the SRR plane and the incident E is parallel to the gap-bearing sides of the SRR. This is manifested by a dip in the transmission spectrum. A simple analytic model is introduced to explain this interesting behavior.Comment: 4 pages, 4 figure
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