Surface-mode lifetime and the terahertz transmission of subwavelength hole arrays

Isaac, T. H.; Barnes, William; Hendry, Euan

doi:10.1103/physrevb.80.115423

Cited by 19 publications

(24 citation statements)

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“…The modeled modulation for the given fluence is actually slightly higher than that measured in experiment; this is because we do not fully recover the narrow mode width for transmission through the smallest holes-the instrumental frequency resolution of the terahertz spectrometer is limited by reflections within the silicon substrate. 19 Our results suggest that if one could limit the intrinsic losses in an array of very small holes fabricated on a semiconductor, the photomodulation effect could become extremely efficient. Our modeling in Fig.…”

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“…1͒ is formed from a 150-nm-thick film of gold on a silicon substrate. The gold is perforated with a square lattice ͑pitch 100 m͒ of square subwavelength holes-the holes have sides ranging in size from 25 to 85 m. Previous works have shown 6,[17][18][19] that such hole-array structures exhibit EOT at terahertz frequencies. The mechanism underlying the transmission can be considered as a Fano-type picture in which resonances arise from constructive interference between radiation which has been transmitted straight through the holes, and radiation which has been transmitted after coupling to a surface mode on the metal-dielectric interface.…”

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“…20 For a hole array made from lossless materials the lifetime of the surface mode is entirely determined by phase retardation across the width of the holes; i.e., arrays with larger holes exhibit a shorter mode lifetime. 19,20 Through photoexcitation of the silicon surface in these samples one can effectively control this surface-mode-mediated element of the EOT transmission and alter the amplitude of the EOT resonances. 6 In Fig.…”

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“…24. In this technique we measure the electric fields of the transmitted terahertz pulses as time-domain spectra; 19 these can be converted to transmission intensity spectra by taking the Fourier transform of the time-domain pulses, squaring the field amplitude, and normalizing by a reference spectrum.…”

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“…In this work we chiefly discuss the lowest-frequency ͑͗1,0͒͘ resonance as changes to the relative coupling intensity between the higher-order modes are complex and highly dependent on sample geometry. 19 The amplitudes and widths of the transmission resonances are determined by the lifetime of the surface mode mediating the transmission. 20 For a hole array made from lossless materials the lifetime of the surface mode is entirely determined by phase retardation across the width of the holes; i.e., arrays with larger holes exhibit a shorter mode lifetime.…”

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Optical control over transmission of terahertz radiation through arrays of subwavelength holes of varying size

2009

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We modulate the transmission of terahertz ͑THz͒ radiation through periodic arrays of subwavelength holes in a metallic film by using pulses of visible-wavelength light to photoexcite the semiconducting substrate of the hole arrays. By varying the photodoping level of the semiconductor we are able to switch off the resonant transmission of THz radiation through the array. By varying the size of the holes, we demonstrate the crucial role that surface modes play in the resonant transmission and ultimately in the photomodulation behavior of these structures. We demonstrate that the surface-wave transmission mechanism can allow for very efficient optical modulation of radiation transmission. DOI: 10.1103/PhysRevB.80.193412 PACS number͑s͒: 71.45.Gm, 41.20.Jb, 84.40.Ϫx Photonic structures which incorporate some degree of dynamic control over their electromagnetic properties 1,2 are interesting for numerous reasons. Some structures have direct applications in proposed photonic devices; in others the dynamic control can provide direct evidence for transmission pathways and for the role of material properties in determining the behavior of a structure. 3 Manipulating material properties optically 4-10 is of particular interest, as changes to the structure can be made on the same time scale as the transit of light pulses through the system.One very fundamental photonic structure is an array of subwavelength holes perforated in a conducting screen. Such arrays can exhibit narrow transmission resonances 11 for wavelengths determined by the periodicity of the array-this is known as extraordinary optical transmission or EOT. The mechanisms underlying EOT in these arrays have been the subject of considerable debate, 12-14 however consensus has gradually emerged that for many structures the transmission is mediated at least in part by electromagnetic surface modes at the interface between the perforated conducting screen and the dielectric layers by which it is bound. 15,16 In this contribution we use pulses of visible light to modulate the transmission of terahertz ͑THz͒ radiation through periodic arrays of subwavelength holes in a metallic film fabricated at the interface of a substrate of crystalline silicon. By varying the photodoping level of the silicon we are able to switch off EOT of THz radiation through the array. By varying the size of the holes we are able to explain the photomodulation effects in terms of the properties of the surface mode which mediates the enhanced transmission; in particular, we can make a direct link between the lifetime of the surface mode and the magnitude of the photomodulation. We show that if we extend the surface-mode lifetime by minimizing losses and reducing the hole size it is possible to attain photomodulation levels which are orders of magnitude greater than those found for a plain silicon surface.The hole-array structure we shall consider in this work ͑Fig. 1͒ is formed from a 150-nm-thick film of gold on a silicon substrate. The gold is perforated with a square lattice ͑pitch 10...

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Optical control over transmission of terahertz radiation through arrays of subwavelength holes of varying size

2009

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Programmable Controls of Multiple Modes of Spoof Surface Plasmon Polaritons to Reach Reconfigurable Plasmonic Devices

Wang

Feng

Tang

et al. 2019

Adv Materials Technologies

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conductors (PECs) instead of plasmas with negative permittivity. In order to realize similar SPPs at low frequencies, the concept of spoof surface plasmon polaritons (SSPPs) was proposed since 2004 by decorating a series of 3D periodically artificial structures on the metal surface. [2][3][4][5][6] To overcome the complexity of 3D structures, an ultrathin corrugated metallic strip was proposed in 2013 to support and guide the SSPPs with high confinement even when it was bent, twisted, or wrapped arbitrarily. [7] To integrate such a single-conductor SSPP transmission line with the conventional two-conductor microwave transmission lines efficiently, some matching transitions were proposed to make a smooth conversion between the SSPP modes and traditional guided-wave modes. [8,9] Hereafter, many related works have been reported based on SSPPs, [10][11][12][13][14][15][16][17][18][19][20] which have advantages of low transmission loss, highly localized fields, low crosstalk, and so on.Recently, programmable metamaterials and metasurfaces have been developed greatly for the dynamic manipulation of electromagnetic (EM) waves, which give the possibility for a single device to possess different functionalities that can be electrically switched through field programming. [21][22][23][24][25][26][27] However, only a few works for the dynamic manipulation of SSPPs have been reported at both terahertz [28][29][30] and microwave [16,[31][32][33][34][35] frequencies, and that most of them are simply tunable SSPPs rather than programmable ones. For example, by placing the split-ring resonators (SRRs) close to the plasmonic waveguide, the resonance of the SRR will introduce a narrow rejection band, whose central frequency can be tuned by controlling the resonant response of the SRRs. [15,16,31] However, these designs usually suffer from the shortcomings of narrow rejection band and poor stability due to the strong resonance of the SRRs. Recently, the concepts of programmable SSPPs to realize three digital-analog functionalities, [36] reconfigurable SSPPs to realize frequency spectrum tunable SSPPs filter, [37] and tunable spoof surface plasmon transmission line (SSP-TL) to construct a compact and frequency-reconfigurable Wilkinson power divider [38] have been proposed one after another. However, they can only control the fundamental mode of SSPPs.Spoof surface plasmon polaritons (SSPPs) can be supported and propagated on metal surfaces decorated with periodic subwavelength structures, whose dispersion properties are determined by geometrical dimensions of unit structures. However, the functions of plasmonic devices made of the conventional passive SSPPs will be fixed once the devices are fabricated. Here, an electronically controlled programmable SSPP waveguide is presented, whose dispersions can be manipulated in real time at fast speed by programing the bias voltage instead of changing the dimensions of the unit structures. There are three different modes at different frequency bands, with a forbidden band existing between the...

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Terahertz Plasmonic Structures

Baragwanath

Gallant

Chamberlain

2012

Terahertz Spectroscopy and Imaging

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Surface-mode lifetime and the terahertz transmission of subwavelength hole arrays

Cited by 19 publications

References 29 publications

Optical control over transmission of terahertz radiation through arrays of subwavelength holes of varying size

Optical control over transmission of terahertz radiation through arrays of subwavelength holes of varying size

Programmable Controls of Multiple Modes of Spoof Surface Plasmon Polaritons to Reach Reconfigurable Plasmonic Devices

Terahertz Plasmonic Structures

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