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Subject: search.filters.subject.Photonic crystals

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    Nonlinear frequency conversion effect in a one-dimensional graphene-based photonic crystal
    (2015-01-01)
    Wicharn, S.
    ;
    Buranasiri, P.
    In this research, the nonlinear frequency conversion effect based on four-wave mixing (FWM) principle in a onedimensional graphene-based photonics crystal (1D-GPC) has been investigated numerically. The 1D-GPC structure is composed of two periodically alternating material layers, which are graphene-silicon dioxide bilayer system and silicon membrane. Since, the third-order nonlinear susceptibility χ<sup>(3)</sup> of bilayer system is hundred time higher than pure silicon dioxide layer, so the enhancement of FWM response can be achieved inside the structure with optimizing photon energy being much higher than a chemical potential level (μ) of graphene sheet. In addition, the conversion efficiencies of 1DGPC structure are compared with chalcogenide based photonic structure for showing that 1D-GPC structure can enhance nonlinear effect by a factor of 100 above the chalcogenide based structure with the same structure length.
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    Efficient third-harmonic generation in one-dimensional photonic crystals
    (2013-09-18)
    Wicharn, S.
    ;
    Buranasiri, P.
    ;
    Ruttanapun, C.
    ;
    Jindajitawat, P.
    In this paper, we have solved nonlinear coupled-mode equations valid for light propagation in a one-dimensional photonic crystal by using numerical expression. Moreover, the medium in this problem has been considered as a nonlinear x <sup>(3)</sup> material. The numerical results have been used to calculate the conversion efficiency in nondepleted-pump limit. The results have been shown us that the maximum conversion efficiency of third-harmonic generation could be occurred when the fundamental field has been tuned near the lower band-edge of photonic band-gap that band-edge phase matched condition has been satisfied. © 2013 SPIE.
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    Parametric down conversion process in one dimensional-photonic band gap structure
    (2012-04-18)
    Wicharn, S.
    ;
    Buranasiri, P.
    In this paper we have numerically investigated the parametric down conversion process in one dimensional-photonic band gap (1D-PBG) structure, which is composed of linear and nonlinear dielectric layers, under four wave mixing phenomena. The nonlinear dielectric layer is material with third-order nonlinear susceptibility χ <sup>(3)</sup>. First, we used coupled-mode theory and slowly varying amplitude approximation to derive a complete set of nonlinear coupled mode equations (NLCMEs) for the FWM phenomena. Then, we have solved these NLCMEs by using undepleted pump approximation. We have got the solution for amplitude of signal and idler waves. Finally, we have used these solutions to calculate the down-converted frequency conversion efficiency. We found that the conversion efficiency can be enhanced by increasing the number of periodic layers and χ <sup>(3)</sup> value. Meanwhile, the conversion efficiency is decreased by increasing of phase mismatch (Δk). © 2012 SPIE.
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    High refractive index dielectric prepared by electron beam evaporation for photonic crystal optical biosensor application
    (2010-02-05)
    Saekow, B.
    ;
    Porntheeraphat, S.
    ;
    Rahong, S.
    ;
    Jaruvanawat, S.
    ;
    Nukeaw, J.
    The fabricated photonic crystal biosensor device consists of SOG material and titanium dioxide (TiO<inf>2</inf>) thin films as low and high refractive indexes dielectric layers, respectively. Nano-Imprinting Lithography (NIL) process was used to duplicate periodic line as grating structure from Ni-master mold onto SOG/glass. High refractive index dielectric thin film layer was deposited by using electron beam evaporation system. The surface morphology and thickness of thin film are characterized by atomic force microscope (AFM) and field emission scanning electron microscope (FE-SEM), respectively. The optical measurement system is set up to observed the sensitivity of fabricated device. A shift of reflected peak wavelength observed from DI-water and IPA was tested. The morphology and the thickness of the prepared dielectric thin films are affected to the efficiency of fabricated device. © (2010) Trans Tech Publications.