The transition from a TEM-like mode to a plasmonic mode in parallel-plate waveguides

Liu, Jingbo; Mendis, Rajind; Mittleman, Daniel M.

doi:10.1063/1.3598404

Cited by 36 publications

(15 citation statements)

References 21 publications

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“…In this situation, these modes interfere destructively at the waveguide center and constructively at the edges, leading to the enhanced electric field near the waveguide edges, similarly to the effect discussed in Ref. 12. In our case, however, this distribution is clearly attributed to the interference of the TEM and TE 02 modes rather than to the formation of plasmon modes .…”

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confidence: 41%

Mode interference and radiation leakage in a tapered parallel plate waveguide for terahertz waves

Mueckstein

Navarro‐Cía

Mitrofanov

2013

Applied Physics Letters

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To exploit tapered parallel plate waveguides for broadband terahertz (THz) spectroscopy, the impact of the waveguide geometry on transmission of terahertz pulses is investigated experimentally. We find that the approximation of single transverse electro-magnetic mode propagation is insufficient for describing the observed behavior. The TE02 mode plays a particularly important role. The mode composition, however, can be controlled by the gap between the waveguide plates, which affects the main loss mechanism, radiation leakage, and group velocity for the TE02 mode. Balancing the waveguide loss and coupling efficiencies results in an optimal gap for the tapered waveguide.

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contrasting

confidence: 41%

Mode interference and radiation leakage in a tapered parallel plate waveguide for terahertz waves

Mueckstein

Navarro‐Cía

Mitrofanov

2013

Applied Physics Letters

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“…Recently, a method based on scattering of the field from needle tip inserted into the waveguide was demonstrated. 10 In this paper, we present a non-invasive method for characterization of the propagating electric field inside a TPPWG. We adapt the air bias coherent detection (ABCD) technique 11 and apply it to a TPPWG in order to image the THz electric field distribution inside the waveguide along the propagation direction without disturbing the propagation of the guided THz wave.…”

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confidence: 99%

Non-invasive terahertz field imaging inside parallel plate waveguides

Iwaszczuk

Andryieuski

Lavrinenko

et al. 2011

Applied Physics Letters

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“…A mature THz technology not only requires THz sources and detectors but also devices to guide and manipulate THz waves. The latter include reflectors [8,9], waveguides [10,11], splitters [12], lenses [13] and modulators [14][15][16]. Modulators could be based on liquid crystals (LCs) as demonstrated by Pan et al [17] who demonstrated for instance switchable phase shifters and filters.…”

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confidence: 97%

Molecular Terahertz Polarizability of PCH5, PCH7, and 5OCB

Vieweg

Shakfa

Koch

2011

J Infrared Milli Terahz Waves

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In this letter we determine the principal and main polarizabilities of the nematic liquid crystals PCH5, PCH7 and 5OCB. The polarizabilities are calculated from the terahertz refractive indices using Vuks' approximation. 5OCB, which has two phenyl rings in its core, shows the highest terahertz anisotropy.Presently terahertz technology is developing at a rapid pace [1,2]. Many applications are foreseen for THz systems, which range from non-destructive testing [3][4][5] and process monitoring in the industry [4, 5] to short-range communications with THz carrier waves [6,7]. A mature THz technology not only requires THz sources and detectors but also devices to guide and manipulate THz waves. The latter include reflectors [8,9], waveguides [10, 11], splitters [12], lenses [13] and modulators [14-16]. Modulators could be based on liquid crystals (LCs) as demonstrated by Pan et al. [17] who demonstrated for instance switchable phase shifters and filters. Wilk et al. presented an LC based switchable THz Bragg structure [18] and Khoo et al. [19] reported on a tunable metamaterial. Yet, in order to design efficient THz devices the dielectric THz properties of the LCs have to be know precisely [20]. Even more important is that the THz absorption is low but other key parameters such as the birefringence are high. The dielectric properties are determined by the molecular polarizability (MP) of the respective materials. Knowledge of the molecular polarizability and how it depends on the molecular structure is, hence, important for designing LC molecules with desired THz properties. In other words the structure-property relations which are well known in the optical frequency range have to be determined also for THz frequencies. The molecular terahertz polarizabilities of three different cyanobiphenyl (CB) molecules were recently presented by Vieweg et al. [21] and the impact of the alkyl chain length has been discussed. To investigate the influence of the core structure we present here the MPs of another three nematic molecules: PCH5, PCH7, and 5OCB.Nematic LCs are rod like molecules and possess a certain degree of orientational order in their nematic phase. Two different polarizabilities can be determined for the LCs i.e. the principal and the main polarizabilities. First, we discuss the principal polarizabilities K o and z e for ordinary and extraordinary polarization, respectively. The LC molecules prefer an orientation along a mean direction. The mean direction is described by the director n ! . The principal polarizabilities z o and z e are deduced from refractive index data [20] measured with the THz field polarized parallel (e, extraordinary) or perpendicular (o, ordinary) to the director. The link between the macroscopic refractive indices and the microscopic principal polarizabilities is given by Vuks' approximation [22].In this formula n o and n e are the THz refractive indices [20], n 2 ¼ 1 3 n 2 e þ 2 3 n 2 o is the square of the mean refractive index and N is the number of molecules per unit volume [23,24]. Secon...

show abstract

The transition from a TEM-like mode to a plasmonic mode in parallel-plate waveguides

Cited by 36 publications

References 21 publications

Mode interference and radiation leakage in a tapered parallel plate waveguide for terahertz waves

Mode interference and radiation leakage in a tapered parallel plate waveguide for terahertz waves

Non-invasive terahertz field imaging inside parallel plate waveguides

Molecular Terahertz Polarizability of PCH5, PCH7, and 5OCB

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