THz imaging and sensing for security applications—explosives, weapons and drugs

Federici, John F.; Schulkin, Brian; Huang, Feng; Gary, Dale E.; Barat, Robert; Oliveira, Filipe; Zimdars, David

doi:10.1088/0268-1242/20/7/018

Cited by 1,563 publications

(687 citation statements)

References 62 publications

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“…Such devices are required for weather radar applications, for tracking nano-satellites and space debris, as well as for plasma diagnostics, volcano monitoring, and quality control of pharmaceutical products, and for the study of historical artefacts. [1][2][3] In recent work, [4][5][6] it has been suggested that periodic patterns machined on the inner surface of a cylindrical conductor exhibit properties of a thin dielectric layer allowing such phenomena as Cherenkov instabilities to be observed. In particular this is an attractive possibility for creating high-intensity sources of THz radiation driven by mildly relativistic electron beams, as such structures should allow very effective heat, stress, and electric charge management via their quick dissipation into the main body "sink" of the material.…”

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confidence: 99%

Surface field excitation by an obliquely incident wave

Konoplev

Phipps

Phelps

et al. 2013

Applied Physics Letters

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confidence: 99%

Surface field excitation by an obliquely incident wave

Konoplev

Phipps

Phelps

et al. 2013

Applied Physics Letters

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“…5 While much spectroscopic information can be obtained from pellet samples, in many cases their THz spectra exhibit broad line shapes due to intrinsic line broadening mechanisms, and to effects related to pellet preparation. 6 A promising method for investigating the THz properties of organic solids is through the use of THz waveguides. [7][8][9] For waveguide terahertz timedomain spectroscopy ͑THz-TDS͒ the parallel plate metal waveguide ͑PPWG͒ is particularly useful because of the nondispersive and low loss propagation for the transverse electromagnetic mode.…”

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Line narrowing of terahertz vibrational modes for organic thin polycrystalline films within a parallel plate waveguide

Melinger

Laman

Harsha

et al. 2006

Applied Physics Letters

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Waveguide terahertz time-domain spectroscopy is used to demonstrate the narrowing of vibrational lines for a thin polycrystalline film of 1,2-dicyanobenzene in a parallel plate metal waveguide. When compared to corresponding linewidths for 1,2-dicyanobenzene in a pellet sample at room temperature, the linewidths for the waveguide film are found to be significantly sharper. For measurements near 77 K, a dramatic line narrowing is observed for the waveguide film, yielding linewidths as much as five times sharper than found in the pellet. These effects are attributed to much smaller inhomogeneous broadening in the waveguide film and result in a more informative spectrum. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2405884͔A standard method for measuring terahertz ͑THz͒ spectra of organic solids is to form a pellet that contains a small quantity of the target solid dispersed in a much larger quantity of a low absorbance host material such as polyethylene. A wide range of organic and bio-organic materials in the form of such pellets has been studied in the THz region, including explosives materials 1 and their by-products, 2 conjugated oligomers, 3 amino acids, 4 and DNA. 5 While much spectroscopic information can be obtained from pellet samples, in many cases their THz spectra exhibit broad line shapes due to intrinsic line broadening mechanisms, and to effects related to pellet preparation. 6 A promising method for investigating the THz properties of organic solids is through the use of THz waveguides. 7-9 For waveguide terahertz timedomain spectroscopy ͑THz-TDS͒ the parallel plate metal waveguide ͑PPWG͒ is particularly useful because of the nondispersive and low loss propagation for the transverse electromagnetic mode. 7,9 The high detection sensitivity that is possible with the PPWG has recently been demonstrated by the THz-TDS characterization of nanometer thick water layers. 9 In addition, the PPWG is easily opened, and the exposed flat inner surfaces are ideal for coating with a thin film of the investigated material.In this letter we demonstrate the application of a PPWG to the terahertz TDS characterization of a solid organic thin polycrystalline film. The material 1,2-dicyanobenzene ͑12DCB͒ is studied because of its relatively strong vibrational lines in the THz region. 10 The major finding of this study is that the THz spectrum of a waveguide polycrystalline film can display significantly sharper vibrational linewidths than found in the corresponding THz spectrum of the pellet. For measurements performed near 77 K, a dramatic line narrowing was observed for the waveguide film, yielding linewidths as much as five times sharper than found in the pellet sample. The line narrowing effect revealed additional vibrational structure in the waveguide film which is not apparent in the pellet. We attribute the line narrowing to a reduction of inhomogeneous broadening for the 12DCB polycrystalline film drop cast on the metal waveguide surface. We also demonstrate the high sensitivity of the waveguide techniq...

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“…Such laser source emitting tunable THz radiation is of great interest for a number of applications, including indoor communications [27,28], biomedical imaging [29,30], spectroscopy [31,32], homeland security and defense [33,34], among others.…”

Section: Discussionmentioning

confidence: 99%

Compact All-Quantum-Dot-Based Tunable THz Laser Source

Fedorova

Gorodetsky

Rafailov

2017

IEEE J. Select. Topics Quantum Electron.

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Abstract-We demonstrate an ultra-compact, roomtemperature, tunable terahertz (THz) generating laser source based on difference-frequency-driven photomixing in a coplanar stripline InAs/GaAs quantum-dot (QD) antenna pumped by a broadly-tunable, high-power, continuous wave InAs/GaAs QD laser diode in the double-grating quasi-Littrow configuration. The dual-wavelength QD laser operating in the 1150 nm -1301 nm wavelength region with a maximum output power of 280 mW and with tunable difference-frequency (277 GHz -30 THz) was used to achieve tunable THz generation in the QD antenna with a photoconductive gap of 50 µm. The best THz output performance was observed at pump wavelengths around the first excited state of the InAs/GaAs QDs (~1160nm), where a maximum output power of 0.6 nW at 0.83 THz was demonstrated.

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THz imaging and sensing for security applications—explosives, weapons and drugs

Cited by 1,563 publications

References 62 publications

Surface field excitation by an obliquely incident wave

Surface field excitation by an obliquely incident wave

Line narrowing of terahertz vibrational modes for organic thin polycrystalline films within a parallel plate waveguide

Compact All-Quantum-Dot-Based Tunable THz Laser Source

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