Superprism effect in magneto-photonic crystals
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J2.5.1
Superprism effect in magneto-photonic crystals A. P. Vinogradov1, A. M. Merzlikin1, A. B. Granovsky2, M. Inoue3,4, A. B. Khanikaev3 1Institute of Theoretical and Applied Electromagnetism, OIVT, Russian Academy of Sciences, 125412, Moscow, Izhorskay 13/19, Russia 2Faculty of Physics, Lomonosov MSU, Leninski Gory, Moscow 119992, Russia 3Department of Electrical and Electronic Engineering, Toyohashi University of Technology, 1-1, Hibari-Ga-Oka, Tempaku, Toyohashi 441-8580, Japan 4CREST, Japan Science and Technology Agency, Saitama, Japan ABSTRACT In frame of computer simulation we study for the first time the magnetic superprism effect. We employ a simple square lattice model and restrict ourselves to lossless case. The photonic band structure for 2D PC built up of magneto-optical matrix with square holes is calculated. It is shown that an external magnetic field applied perpendicularly to the holes changes 2D PC band structure and thus propagation of light through PC. The effect exists even for a weak magneto-optical activity of the matrix but only for the definite set of model parameters. Thus, it makes possible to deflect a light beam by applying magnetic field without variation of frequency or initial angle of incidence. INTRODUCTION One of the brightest manifestations of the PC properties is the effect of a “superprism”, in which a small (of the order of a degree or less) variation of the angle of incidence of an electromagnetic wave may result in significant (more than hundreds of degrees) deviation of a refracted wave [1-3]. Actually, this effect is rather due to diffraction but refraction. Indeed, since the surface of a photonic crystal is a diffraction grating it splits the incident wave into several lobes. At a proper choice of the PC cut, incidence angle of and frequency of the electromagnetic wave, it is possible to obtain two non-evanescent lobes: one central and one side lobe. Selecting the shape of inclusion and symmetry of the PC lattice, it is possible to achieve the situation where the side lobe cannot propagate because it locates in the photonic band gap. Thus, we have only one wave propagating through the PC, like in ordinary refraction. The small variation of the angle of incidence leads to the small change in the directions of propagation of the lobes. The superprism effect is observed if the side lobe initially directing the forbidden direction is redirected into allowed one and vice versa the central lobe initially directing the allowed direction is redirected into forbidden one. Thus, the role of the “refracted” wave is now played by the side lobe and the angle of such a “refraction” changes considerably much than the angle of incidence. The effect is observed not only when one changes the angle of incidence but also the frequency. Moreover, Joannopoulos and co-authors [4] suggested a device based on the superprism effect, which can deflect a light beam at the fixed frequency and angle of incidence. This device includes a permeable prism (controlling part) and a slab of PC. In the prese
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