Essential parameter in the formation of photonic band gaps

Kee, Chul‐Sik; Kim, Jae Eun; Park, Hae Yong; Kim, S. J.; Song, Hyun-A; Kwon, Young–Se; Myung, Noh‐Hoon; Shin, Sangho; Lim, H.

doi:10.1103/physreve.59.4695

Cited by 50 publications

(13 citation statements)

References 12 publications

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“…3(b). This result is reasonable since the positions of photonic band gaps depend on the wave impedance ratio of two components [82,83], while the latter changes with the NLC's permittivity in the present case. For a rough estimation, the central wavelength of the NLC-based MPC structure can be evaluated by λ c = 2…”

Section: Electrically-controlled Magneto-optical Effects In Magnetophsupporting

confidence: 51%

Manipulating Nematic Liquid Crystals-based Magnetophotonic Crystals

Li¹

2009

New Developments in Liquid Crystals

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Section: Electrically-controlled Magneto-optical Effects In Magnetophsupporting

confidence: 51%

Manipulating Nematic Liquid Crystals-based Magnetophotonic Crystals

Li¹

2009

New Developments in Liquid Crystals

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“…In guiding a microwave through a micro strip line, the wavelength depends upon the effective dielectric constant of the substrate eff , for w/h Ն 1, it is given as [9] eff ϭ ͑ 1 ϩ 2 ͒/2 ϩ ͑ 1 Ϫ 2 ͒/2*͑1 ϩ 12h/w͒ Ϫ1/ 2 ,…”

Section: Resultsmentioning

confidence: 99%

Photonic band gap studies on periodic metallic structures in the microwave region

Tiwari

Gupta

et al. 2002

Micro & Optical Tech Letters

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ABSTRACT:We present our experimental findings on microstrip-type metallic photonic band gap (PBG) INTRODUCTIONPeriodic dielectric structures exhibit photonic band gap (PBG), that is, certain band of frequencies of the em wave are prohibited to propagate through the structures [1,2]. Such periodic dielectric structures have been called photonic crystals.Photonic crystals have a wide range of applications in microwave and millimeter-wave devices such as filters, switches, cavity resonators, and antennas and are useful in applications requiring frequency-selective surfaces, etc. [3][4][5]. The problem of absorption of electromagnetic waves in the substrate can be minimized with the use of PBG substrate, and more efficient microwave circuits can be fabricated. For example, in the microwave region PBG structures have been used to improve the radiation efficiency of antennas, as well as in broadband absorbers [4].Efforts are being made to develop one-, two-, and three-dimensional PBG structures exhibiting wide band gaps in the optical and microwave regions using periodic structures on materials like metals, heterostructures of dielectric and metal, and magnetic materials [6 -9]. It has been supposed that the variation of dielectric constant or refractive index ͌ () gives rise to PBG crystals. But recently, in certain cases, it was found that the wave impedance ͌ (/) plays an important role in the formation of PBG. For example, wide gaps have been observed in purely metallic structures. These PBG structures have an advantage that they are almost perfect reflectors in the low frequency regions, are easy to fabricate and provide wide band gap, as compared to conventional structures designed with dielectrics [10].In this paper, we report our experimental findings on metallic periodic structure prepared using commercial aluminum foil. The effect of variation of periodicity, fill factor, and defect length on photonic band gap has been studied and the results are presented. THEORYIt is known that a strong periodic variation in the dielectric constant or refractive index gives rise to PBG. In microwave-integrated circuits, a microstripline can be used as a waveguide or as a transmission line consisting of low-loss dielectric substrate sandwitched between a metallic ground plane and a stripline [4]. Periodic structures can be drawn in the ground plane. The periodic array of holes introduced in the stripline affects the modes of a guided microwave signal because the geometry of the waveguide changes periodically along the stripline.For the spatial period of the array of holes a, the guided modes can be characterised by a wave vector between Ϫ/2 and /2 because of the translational symmetry along the strip line. This results in the periodic perturbation at Ϫ/2 to /2, and forms the modes which create the splitting at the Brillouin zone, which is known as PBG. The low-frequency modes concentrate their energy in the high-regions and the high frequency modes concentrate their energy in the low-regions. When the transmission frequen...

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“…Hence, we can conclude that in the case of planar transmission lines showing some periodicity, the bandgap effect is observed when a strong variation of characteristic impedance occurs (from Z c uni diel ϭ 56⍀ to Z c uni air ϭ 117⍀). This fact was already acted upon by Kee et al [9,10] for the case where the effective dielectric constant does not change along the periodic structure (where air was used as a uniform substrate along the whole structure). Here, we point out the same effect (solid curve in Fig.…”

Section: Topology Under Scopementioning

confidence: 89%

“…By suppressing one hole while keeping the total length of the structure unchanged, we in fact create defects in a manner that differs from the usual one. First, instead of modifying the physical length of one section, as done by Kee et al [9] and Tiwary et al [11], we change its dielectric nature; hence, we modify both its electrical length via its effective refractive index or dielectric constant (increased from eff uni air to eff uni diel ) and its characteristic impedance (lowered from Z cuni air to Z c uni diel ). Secondly, in this paper we illustrate the influence of the position of the defect inside the array.…”

Section: Topology Under Scopementioning

confidence: 99%

“…For many years, the existence of the PBG was associated with the periodic change in the refractive index along the material under scope. To our best knowledge, only the work by Kee et al [9,10] associated (for the first time) the existence of the stop band in PBG materials and devices with a periodic change of the wave impedance, induced by a change of the dielectric and/or magnetic properties of the mate- rial. The concept was then confirmed by Tiwary et al [11].…”

Section: Introductionmentioning

confidence: 99%

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Experimental demonstration of the origin of photonic bandgap creation and associated defect modes in microwave planar circuits

Saib¹,

Platteborze²,

Huynen³

2004

Micro & Optical Tech Letters

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We have measured the relative complex permittivity of epoxy resinous material under changes in temperature. The variation of the temperature of the single-layer absorber has been analyzed using the FDTD-HTE method. As a result, the following three aspects were confirmed:1. If the relative complex permittivity of the sample depends on the temperature, its real part increases from 14.7 to 16.8, and its imaginary part increases from 1.5 to 4.2 under the condition that the temperature increases from 24°C to 160°C. 2. The temperature inside the single-layer absorber increases rapidly with increased irradiation power. It is observed that the heat generated inside the absorber tends to equal to heat radiated from the surface of one after 120 min of irradiation. The stabilization temperatures are about 40°C at 100 W/m 2 , about 110°C at 500 W/m 2 , and about 170°C at 1000 W/m 2 . 3. The absorption of the absorber becomes 25 dB in the initial state. Then the absorption increases gradually, shows a peak value of about 60 dB, and decreases gradually after that.In the near future, we would like to measure the temperature characteristics of various materials for the radiowave absorbers. Moreover, we will also try to examine the absorption characteristics of other types of radiowave absorbers under irradiation power.

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Essential parameter in the formation of photonic band gaps

Cited by 50 publications

References 12 publications

Manipulating Nematic Liquid Crystals-based Magnetophotonic Crystals

Manipulating Nematic Liquid Crystals-based Magnetophotonic Crystals

Photonic band gap studies on periodic metallic structures in the microwave region

Experimental demonstration of the origin of photonic bandgap creation and associated defect modes in microwave planar circuits

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