The 2017 terahertz science and technology roadmap

Dhillon, Sukhdeep; Vitiello, Miriam S.; Linfield, Edmund H.; Davies, A. G.; Hoffmann, Matthias C.; Booske, John H.; Paoloni, Claudio; Gensch, Michael; Weightman, P.; Williams, Gwyn; Castro-Camus, E.; Cumming, David R. S.; Simoens, F.; Carranza, Ivonne Escorcia; Grant, James P.; Lucyszyn, S.; Kuwata‐Gonokami, Makoto; Konishi, Kuniaki; Koch, Martin; Schmuttenmaer, Charles A.; Cocker, Tyler L.; Huber, Rupert; Markelz, Andrea; Taylor, Zachary D.; Wallace, Vincent P.; Zeitler, J. Axel; Šibík, Juraj; Korter, Timothy M.; Ellison, Brian N.; Rea, Simon; Goldsmith, Paul F.; Cooper, Ken B.; Appleby, Roger; Pardo, Diego; Huggard, P. G.; Krozer, Viktor; Shams, Haymen; Fice, Martyn J.; Renaud, Cyril C.; Seeds, A.J.; Stöhr, A.; Naftaly, Mira; Ridler, N M; Clarke, Roland; Cunningham, J. E.; Johnston, Michael B.

doi:10.1088/1361-6463/50/4/043001

Cited by 1,316 publications

(626 citation statements)

References 183 publications

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“…topological insulator properties) [89]. It is worth mentioning the importance of this new class of device for amplitude and frequency stabilization of QCLs in metrological grade spectroscopy [90][91][92][93]. Naming all the possible applications of THz active devices in gas-and solid-state spectroscopy, from sensing to healthcare to investigation of novel state of matter and materials, could be per se the topic of another review, as the one reported recently in Ref.…”

Section: Applicationsmentioning

confidence: 97%

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All-integrated terahertz modulators

et al. 2017

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Terahertz (0.1-10 THz corresponding to vacuum wavelengths between 30 μm and 3 mm) research has experienced impressive progress in the last few decades. The importance of this frequency range stems from unique applications in several fields, including spectroscopy, communications, and imaging. THz emitters have experienced great development recently with the advent of the quantum cascade laser, the improvement in the frequency range covered by electronic-based sources, and the increased performance and versatility of time domain spectroscopic systems based on full-spectrum lasers. However, the lack of suitable active optoelectronic devices has hindered the ability of THz technologies to fulfill their potential. The high demand for fast, efficient integrated optical components, such as amplitude, frequency, and polarization modulators, is driving one of the most challenging research areas in photonics. This is partly due to the inherent difficulties in using conventional integrated modulation techniques. This article aims to provide an overview of the different approaches and techniques recently employed in order to overcome this bottleneck.

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Section: Applicationsmentioning

confidence: 97%

“…Naming all the possible applications of THz active devices in gas-and solid-state spectroscopy, from sensing to healthcare to investigation of novel state of matter and materials, could be per se the topic of another review, as the one reported recently in Ref. [93].…”

Section: Applicationsmentioning

confidence: 99%

All-integrated terahertz modulators

et al. 2017

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“…Spectroscopy and imaging with pulsed terahertz (THz) radiation have been demonstrated as powerful tools for materials characterization and identification [1][2][3], non-destructive inspection [4], safety scans for security [5] and medical examination [6,7]. THz photoconductive antennas (based on Auston switches [8]) have been developed over the last 30 years and have now established themselves as reliable and effective detection elements used in many commercial pulsed THz systems, including THz time-domain spectroscopy (THz-TDS) systems [9].…”

Section: Introductionmentioning

confidence: 99%

Distinguishing cap and core contributions to the photoconductive terahertz response of single GaAs based core–shell–cap nanowire detectors

Peng

Parkinson²,

et al. 2018

physics

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GaAs nanowires are promising candidates for advanced optoelectronic devices, despite their high surface recombination velocity and large surface-area-to-volume ratio, which renders them problematic for applications that require efficient charge collection and long charge-carrier lifetimes. Overcoating a bare GaAs nanowire core with an optimized larger-bandgap AlGaAs shell, followed by a capping layer of GaAs to prevent oxidation, has proven an effective way to passivate the nanowire surface and thereby improve electrical properties for enhanced device performance. However, it is difficult to quantify and distinguish the contributions between the nanowire core and cap layer when measuring the optoelectronic properties of a nanowire device. Here, we investigated the photoconductive terahertz (THz) response characteristics of single GaAs/AlGaAs/GaAs core-shell-cap nanowire detectors designed for THz time-domain spectroscopy. We present a detailed study of the contributions of the GaAs cap layer and GaAs core on the ultrafast optoelectronic performance of the detector. We show that both the GaAs cap and core contribute to the photoconductive signal in proportion to their relative volume in the nanowire. By increasing the cap volume ratio to above 90% of the total GaAs volume, a quasi-direct-sampling type photoconductive nanowire detector can be achieved that is highly desirable for low-noise and fast data acquisition detection.

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“…Therefore using the most up-to-date laser system reported for our application would hardly allow generating sufficient amount of THz to successfully power a THz-based linear accelerator. In addition to these limitations, further challenges arise when designing the nonlinear medium used for down conversion such as the damage threshold of organic nonlinear crystals at high repetition rate [15], the clear aperture and peak power handling limitations in periodically poled lithium Niobate [16] or the phase transitions in potassium Niobate [17]- [19]. In order to address these challenges, we are investigating two methods dubbed 'cascaded optical parametric amplification' [20], [21] and 'chirp-and-delay' [22] for the generation of multi-cycle THz radiation with NIR driving lasers.…”

Section: Introductionmentioning

confidence: 99%

Frequency-shifted sources for terahertz-driven linear electron acceleration

Hemmer

Cirmi

Ravi

et al. 2018

Nonlinear Frequency Generation and Conversion: Materials and Devices XVII

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The generation of THz-frequency radiation via nonlinear parametric frequency down-conversion has long been driven by the spectroscopy and imaging communities. As a result, little efforts have been undertaken toward the generation of high energy THz-frequency pulses. THz-frequency radiation has however recently been identified has a promising driver for strong-field physics and an emerging generation of compact particle accelerators. These accelerators require THzfrequency pulses with energies in the multi-millijoule range therefore demanding orders of magnitude improvements from the current state-of-the-art. Much can be gained by improving the intrinsically low efficiency of the down-conversion process while still resorting to existing state-of-the-art lasers. However, the fundamental Manley-Rowe limit caps the efficiency of parametric downconversion from 1-µm wavelength lasers to sub-THz frequency to the sub-percent range. We present methods that promise boosting the THz radiation yield obtained via parametric down-conversion beyond the Manley-Rowe limit. Our method relies on cascaded nonlinear three-wave mixing between two spectrally neighboring laser pulses in periodically poled Lithium Niobate. Owing to favorable phase-matching, the down-conversion process avalanches, resulting in spectral broadening in the optical domain. This allows in-situ coherent multiplexing of multiple parametric down-conversion stages within a single device and boosting the efficiency of the process beyond the ManleyRowe limit. We experimentally demonstrated the concept using either broadband, spectrally chirped optical pulses from a Joule-class laser or using two narrowband lasers with neighboring wavelengths. Experimental results are backed by numerical simulations that predict conversion efficiencies from 1 µm to sub-THz radiation in the multi-percent range.

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The 2017 terahertz science and technology roadmap

Cited by 1,316 publications

References 183 publications

All-integrated terahertz modulators

All-integrated terahertz modulators

Distinguishing cap and core contributions to the photoconductive terahertz response of single GaAs based core–shell–cap nanowire detectors

Frequency-shifted sources for terahertz-driven linear electron acceleration

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