Multiple lateral photo-Dember terahertz emitters illuminated by a cylindrical micro-lens array

Gow, Paul C.; Berry, Sam A.; McBryde, Duncan; Barnes, M. E.; Beere, Harvey E.; Ritchie, D. A.; Apostolopoulos, Vasileios

doi:10.1063/1.4850576

Cited by 10 publications

(4 citation statements)

References 11 publications

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“…Since partially masked optical excitation produces an asymmetric carrier concentration in a semiconductor, LPDemitters exhibit enhanced THz emission compared with conventional PD-emitters [171], but concede to modern PCAs. In order to overcome this issue, various types of multiple LPD-emitters, which could compete with modern commercially available PCAs, have been proposed [378]. Obviously, the absence of electrical bias and the rather high efficiency of LPD-emitters make them attractive for use in novel THz systems, which are extensively applied in THz medical diagnosis.…”

Section: Terahertz-wave Delivery To Difficult-to-access Tissue and In...mentioning

confidence: 99%

The progress and perspectives of terahertz technology for diagnosis of neoplasms: a review

Zaytsev

Dolganova

Chernomyrdin

et al. 2019

J. Opt.

165

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Over the past few decades, significant attention has been paid to the biomedical applications of terahertz (THz) technology. Nowadays, THz spectroscopy and imaging have allowed numerous demanding problems in the biological, medical, food, plant and pharmaceutical sciences to be solved. Among the biomedical applications, the label-free diagnosis of malignant and benign neoplasms represents one of the most attractive branches of THz technology. Despite this attractiveness, THz diagnosis methods are still far from being ready for use in medical practice. In this review, we consider modern research results in the THz diagnosis of malignant and benign neoplasms, along with the topical research and engineering problems which restrain the translation of THz technology to clinics. We start by analyzing the common models of THz-wave-tissue interactions and the effects of tissue exposure to THz waves. Then, we discuss the existing modalities of THz spectroscopic and imaging systems, which have either already been applied in medical imaging, or hold strong potential. We summarize the earlier-reported and original results of the THz measurements of neoplasms with different nosology and localization. We pay attention to the origin of contrast between healthy and pathological tissues in the THz spectra and images, and discuss the prospects of THz technology in

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Section: Terahertz-wave Delivery To Difficult-to-access Tissue and In...mentioning

confidence: 99%

The progress and perspectives of terahertz technology for diagnosis of neoplasms: a review

Zaytsev

Dolganova

Chernomyrdin

et al. 2019

J. Opt.

165

View full text Add to dashboard Cite

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“…It is possible to multiplex LPD emitters to increase their performance by fabricating periodic metal strips and illuminating correlating edges [5,6] or by illuminating a periodic wedge pattern uniformly [3,7]. We have also previously demonstrated emitters that use two metals with different work functions and skin depths in overlapping striplines to mask areas of the semiconductor [8].…”

Section: Thz Dipoles Gaas Aumentioning

confidence: 99%

“…A 100 fs, 80 MHz Ti:sapphire laser with the wavelength centred at 780 nm was used to illuminate both the emitter and the detector, with powers of 100 and 6 mW, respectively. The full laser spot size of 1.4 mm was modulated by an optical chopper and used to illuminate the double-metal emitters as a focusing lens for the optical pump and an Si-lens for collimation of the THz output were not required [5,8].…”

Section: Thz Dipoles Gaas Aumentioning

confidence: 99%

Characterisation of THz emission from double‐metal‐patterned gallium–arsenide multiple emitters

Gow¹,

McBryde²,

Berry³

et al. 2014

Electron. lett.

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Multiplexed gallium-arsenide (GaAs)-based terahertz (THz) emitters fabricated with periodic double-metal structures are demonstrated and the effect of different metals on the THz output is investigated. THz emission originates from the lateral photo-Dember effect and from the different Schottky barrier heights of the chosen metal pair. The metal combinations used were Au-Al, Au-Pb and Cu-Cr. The emitters were characterised according to temperature and the highest peak-to-peak THz emission was achieved with the Cu-Cr metal pairing at 150 K.Introduction: Lateral photo-Dember (LPD) emitters have been demonstrated to be robust terahertz (THz) emitters that require no voltage bias to operate [1-3]. An LPD emitter is fabricated by partially masking a semiconductor surface with a deposited metal layer. An ultrafast laser, with above band-gap energy, is focused on the metal-semiconductor boundary. An asymmetrical distribution of photo-generated carriers that are free to diffuse is created near the metal-semiconductor interface. The carriers that diffuse beneath the metal mask form a dipole (dipole B in Fig. 1a), which is quenched due to reflection from the metal surface [4], whereas the carriers that diffuse away from the metal form a dipole (dipole A in Fig. 1a) that is free to radiate and does so parallel to the pump beam.

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“…In this work, we propose to achieve the required asymmetry for co-linear THz emission by applying a low skin depth second metal on one side of each repeat of the metal mask, reducing the quenching strength from one side of the metal mask by reducing the reflectivity of the metal surface 7 . In doing so we eliminate the requirement for a micro-lens array used previously 5 , allowing for the emitters to operate under uniform illumination. The reduced quenching strength allows net terahertz emission to be formed in a dipole pattern under the low skin depth metal.…”

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confidence: 99%

Multiple double-metal bias-free terahertz emitters

McBryde

Gow

Berry

et al. 2014

Applied Physics Letters

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We demonstrate multiplexed terahertz emitters that exhibits 2 THz bandwidth that do not require an external bias. The emitters operate under uniform illumination eliminating the need for a micro-lens array and are fabricated with periodic Au and Pb structures on GaAs. Terahertz emission originates from the lateral photo-Dember effect and from the different Schottky barrier heights of the chosen metal pair. We characterize the emitters and determine that most terahertz emission at 300 K is due to band-bending due to the Schottky barrier of the metal.Comment: 4 pages, 6 figure

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Multiple lateral photo-Dember terahertz emitters illuminated by a cylindrical micro-lens array

Cited by 10 publications

References 11 publications

The progress and perspectives of terahertz technology for diagnosis of neoplasms: a review

The progress and perspectives of terahertz technology for diagnosis of neoplasms: a review

Characterisation of THz emission from double‐metal‐patterned gallium–arsenide multiple emitters

Multiple double-metal bias-free terahertz emitters

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