Enhanced on-chip terahertz vibrational absorption spectroscopy using evanescent fields in silicon waveguide structures

Amarloo, Hadi; Safavi‐Naeini, Safieddin

doi:10.1364/oe.424414

Cited by 20 publications

(10 citation statements)

References 47 publications

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“…Among them, the THz waveguide transmission technology with low loss, long distance, and low dispersion is very essential due to the signal distortion in free space, the attenuation caused by atmospheric scattering, and the water vapor absorption. Various THz waveguides have been proposed and investigated, such as hollow metallic structures [20], metal wires [21], dielectric waveguides [22], parallel plate structures [23], photonic crystal fibers [24], [25], rectangular structures [26], plasmonic [27], and tapered waveguide [28]. However, most of researchers focused on the low loss and low dispersion THz waveguides and paid little attention to the transverse standing waves (i.e., the guided wave modes).…”

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confidence: 99%

Terahertz Resonances of Transverse Standing Waves in a Corrugated Plate Waveguide

Liu

Zhang

et al. 2022

IEEE Photonics J.

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Terahertz (THz) propagation in periodic structures has attracted great attention because of its captivating electrical and optical properties. However, the created THz band gaps are usually considered to be caused by Bragg resonances. Here, we theoretically and numerically investigate THz resonances and their related band gap properties in a periodically corrugated plate waveguide with arbitrary wall profiles. It has been found that the corrugated structure can cause not only the interaction between the same transverse modes, called the Bragg resonance, but also the strong interference between different transverse standing wave modes, which occurs in a higher frequency range with quite different features. Unlike the well-known Bragg resonance, the excited resonances between different transverse modes can produce the stronger energy attenuation and wider frequency band gap. The dispersion diagram is depicted to clearly describe the relationship between these resonances and waveguide geometries. Using this method, we can properly estimate the band gap structure of THz waveguides, which has been confirmed by the simulated results. In addition, these two resonances can be easily manipulated by changing the symmetry of waveguide structures. These findings on THz propagation in periodic waveguides could be applicable in high performance devices, such as filters, modulators and switches.

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confidence: 99%

Terahertz Resonances of Transverse Standing Waves in a Corrugated Plate Waveguide

Liu

Zhang

et al. 2022

IEEE Photonics J.

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“…Traditional absorption spectroscopy measurement facilities usually use more sample materials since the diffraction of terahertz waves. 9 The current measurement of the terahertz absorption spectrum of solid samples processed by the tablet-pressing technique usually requires several hundred milligrams to several grams of the material to be measured. The interaction distance between the terahertz waves and the sample may limit the necessary amount of the samples.…”

Section: Introductionmentioning

confidence: 99%

“…For improving the sensitivity of terahertz absorption spectroscopy detection, additional enhanced structures, including photonic crystal fibers, resonant cavity, metal gratings, metal split ring resonators, and dielectric metasurface structures, are required to boost the interaction between the electromagnetic wave and sample material. Among these structures, the waveguides [9][10][11] and metasurfaces [12][13][14][15] have been treated in the sensing applications. Terahertz dielectric waveguides exhibit the merits of small measurement volume, long interaction length, high signal-to-noise ratio (SNR), and so on.…”

Section: Introductionmentioning

confidence: 99%

“…In this case, it is not conducive to the efficient direct coupling of terahertz waves into the waveguides. 9 In addition, dielectric metagratings 13 and metamaterial structures 16 have been treated to boost the wide-band terahertz absorption spectroscopy of thin film samples. In general, a series of resonance peaks can be obtained by changing the incident angles of the electromagnetic waves or adopting different unit cells in the super cells.…”

Section: Introductionmentioning

confidence: 99%

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Boosting the terahertz absorption spectroscopy based on the stretchable metasurface

Yan

Feng

Yang

et al. 2023

Phys. Chem. Chem. Phys.

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“…Terahertz (THz) waves are extensively used in chemical and biological sensing, [1][2][3] medical [4][5][6] and near-field imaging, [7,8] onchip communication, [9,10] foodstuffs, drug inspections, [11][12][13] and spectroscopy. [14][15][16] Constructing on-chip integrated THz devices carrying energy profiles in subwavelength scale is of great potential for various applications. In visible and near-infrared regimes, exciting surface plasmon polaritons (SPPs), [17][18][19][20] the collective oscillations of electrons at a dielectric metal interface, using Previous studies, such as, the references [47][48][49][50][51][52][53][54][55] have reported the guiding mechanism of IGP.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Image Graphene Polaritons with Extremely Confined Mode and Field Enhancement in the Terahertz Regime

Huang

2022

Advanced Optical Materials

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noble metals, are generally used to compress mode sizes and break the diffraction limit of light. However, the SPPs exhibit highly delocalized mode confinements because noble metals behave as approximately perfect electric conductors in the THz regime, [21][22][23] which leads to a wave vector of the SPPs perpendicular to the interface nearly equal to that of free space THz waves. Such SPPs with a dominant electric field component normal to the tangential interface is called Zenneck [24,25] or Sommerfeld [26,27] waves. Their penetration depths into dielectric regions ranged from several millimeters to several centimeters. To compress mode sizes to deep subwavelength at the THz band, in addition to considering perforating subwavelength textured metal surfaces to create spoof SPPs, [28][29][30][31] graphene, [32,33] a monolayer of carbon atoms bonded in a honeycomb lattice, with the nearly pure imaginary surface conductivity (i.e., metallic features) was considered as one of the promising candidates. The merits of the graphene plasmons (GPs) [34][35][36][37][38] include the atomically thin sheet, reduction of GP wavelength, and tunable GP properties by electric gating and chemical doping in the graphene sheet. Therefore, several graphene-based devices operating in the THz regime, such as absorbers, [39] modulators, [40,41] switch, [42] imaging, [43] and plasmonic waveguides, [44][45][46] use the unique optical properties of graphene.Currently, the THz mode confinements of graphene-based waveguides are limited to the orders from 10 −2 to 10 −4 [44][45][46] of the mode area A 0 = λ 2 /4, where λ is the free space wavelength. To further enhance the mode confinements, a new waveguide configuration [47][48] consisting of a graphene sheet separated from a noble metal substrate by a nanometer dielectric spacer is proposed to support a new kind of GP mode with a highly confined mode size and a linear dispersion [49,50] called acoustic GP (AGP) or image GP (IGP), [51][52][53] which is similar to a symmetric GP of a double-layer graphene structure. [54,55] On the basis of the charge carrier viewpoint, [47][48][49][50][51][52][53] an IGP with an antisymmetric distribution of charge carriers is the hybridization of plasmons in a graphene sheet and its mirror image with out-of-phase charge oscillations inside the metal substrate. On the basis of field coupling, an IGP is explained by coupling a GP field in the graphene with a Zenneck wave in the metal. Therefore, the resultant field is significantly enhanced within the nanoscale spacer between the graphene and metal to provide high-confined electromagnetic fields and high field enhancement.Guiding terahertz waves below the diffraction limit of light typically excite graphene plasmons (GPs). However, the mode confinements of conventional GPs using graphene-dielectric interfaces are limited. To further squeeze the optical mode sizes, a graphene-dielectric-metal (GDM) configuration supporting an image graphene plasmon (IGP) has been reported recently through the plasmon interactio...

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Enhanced on-chip terahertz vibrational absorption spectroscopy using evanescent fields in silicon waveguide structures

Cited by 20 publications

References 47 publications

Terahertz Resonances of Transverse Standing Waves in a Corrugated Plate Waveguide

Terahertz Resonances of Transverse Standing Waves in a Corrugated Plate Waveguide

Boosting the terahertz absorption spectroscopy based on the stretchable metasurface

Hybrid Image Graphene Polaritons with Extremely Confined Mode and Field Enhancement in the Terahertz Regime

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