Noninvasive, near-field terahertz imaging of hidden objects using a single-pixel detector

Stantchev, Rayko I.; Sun, Baoqing; Hornett, Samuel M.; Hobson, Peter A.; Gibson, Graham M.; Padgett, Miles J.; Hendry, Euan

doi:10.1126/sciadv.1600190

Cited by 399 publications

(248 citation statements)

References 47 publications

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“…24 These systems, in fact, exhibit complex transmission properties that cannot be easily interpreted using a time-independent, intensity-based analysis, which constitutes the standard methodology available today. 25 Despite the large body of research in this field, however, one of the practical challenges in implementing field-sensitive THz GI lies in the realization of controllable structured light. 26,27 Spatial-light-modulator (SLM) devices, which are readily accessible at optical frequencies, cannot be easily extended to the THz domain.…”

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confidence: 99%

Time-Resolved Nonlinear Ghost Imaging

et al. 2018

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Terahertz (THz) spectroscopy systems are widely employed to retrieve the chemical and material composition of a sample. This is single-handedly the most important driving motivation in the field and has largely contributed to shaping THz science as an independent subject. The limited availability of high-resolution imaging devices, however, still represents a major technological challenge in this promising field of research. In this theoretical work, we tackle this challenge by developing a novel nonlinear ghost imaging approach that conceptually outperforms established single-pixel imaging protocols at inaccessible wavelengths. Our methodology combines nonlinear THz generation with time-resolved field measurements, as enabled by state-of-theart time domain spectroscopy techniques. As an ideal application target, we consider hyperspectral THz imaging of semitransparent samples with nonnegligible delay contribution, and we demonstrate how time-resolved, full-wave acquisition enables accurate spatiotemporal reconstruction of complex inhomogeneous samples.

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confidence: 99%

Time-Resolved Nonlinear Ghost Imaging

et al. 2018

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“…Near-field THz microscopy has seen tremendous progress over recent years towards very high spatial resolutions [21][22][23][24], and has previously been employed in many successful implementations to explore near-field dynamics in both resonant structures [18,25,26] and apertures [27][28][29][30][31]. In the work of Bitzer et al [25], lattice modes were investigated for the case of split ring resonators (SRR), where the array was shown to hybridize lattice modes with magnetic dipole resonances.…”

Section: Resultsmentioning

confidence: 99%

Terahertz diffraction enhanced transparency probed in the near field

et al. 2017

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Electromagnetically induced transparency in metamaterials allows to engineer structures which transmit narrow spectral ranges of radiation while exhibiting a large group index. Implementation of this phenomenon frequently calls for strong near-field coupling of bright (dipolar) resonances to dark (multipolar) resonances in the metamolecules comprising the metamaterials. The sharpness and contrast of the resulting transparency windows thus depends strongly on how closely these metamolecules can be placed to one another, placing constraints on fabrication capabilities. In this manuscript, we demonstrate that the reliance on near-field interaction strength can be relaxed, and the magnitude of the electromagnetic-induced transparency enhanced, by exploiting the long-range coupling between metamolecules in periodic lattices. By placing dolmen structures resonant at THz frequencies in a periodic lattice, we show a significant increase of the transparency window when the in-plane diffraction is tuned to the resonant frequency of the metamolecules, as confirmed by direct mapping of the THz near-field amplitude across a lattice of dolmens. Through the direct interrogation of the dark resonance in the near field, we show the interplay of near-and far-field couplings in optimizing the response of planar dolmen arrays via diffraction-enhanced transparency.

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“…36 However, single apertures and scatterers produce tiny signals due to their small size with respect to the THz wavelength. 37 To achieve optimum signal-to-noise, we therefore pattern our photoexcitation beam into binary intensity masks derived from Hadamard matrices, 37,38 as explicitly described in ref (37) and in the Supporting Information. Knowledge of the masking patterns and the corresponding far-field detector readout is combined to obtain an image of the THz photoconductivity of the object, our CVD graphene sample.…”

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Subwavelength Terahertz Imaging of Graphene Photoconductivity

et al. 2016

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Using a spatially structured, optical pump pulse with a terahertz (THz) probe pulse, we are able to determine spatial variations of the ultrafast THz photoconductivity with subwavelength resolution (75 μm ≈ λ/5 at 0.8 THz) in a planar graphene sample. We compare our results to Raman spectroscopy and correlate the existence of the spatial inhomogeneities between the two measurements. We find a strong correlation with inhomogeneity in electron density. This demonstrates the importance of eliminating inhomogeneities in doping density during CVD growth and fabrication for photoconductive devices.

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Noninvasive, near-field terahertz imaging of hidden objects using a single-pixel detector

Abstract: Terahertz imaging for noninvasive measurements.

Cited by 399 publications

References 47 publications

Time-Resolved Nonlinear Ghost Imaging

Time-Resolved Nonlinear Ghost Imaging

Terahertz diffraction enhanced transparency probed in the near field

Subwavelength Terahertz Imaging of Graphene Photoconductivity

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