Optimised Spintronic Emitters of Terahertz Radiation for Time-Domain Spectroscopy

Wagner, Ford M.; Melnikas, Simas; Cramer, Joel; Damry, Djamshid A.; Xia, Chelsea Q.; Peng, Kun; Jakob, G.; Kläui, Mathias; Kičas, Simonas; Johnston, Michael B.

doi:10.1007/s10762-022-00897-9

Cited by 4 publications

(4 citation statements)

References 28 publications

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“…Next, we characterised our NW devices for THz sampling. The NWs were exposed to single-cycle electromagnetic pulses, produced by a broadband spintronic THz emitter 25 . The sampling was achieved by optically switching on the NWs by a 35-fs laser pulse with tunability from 1.2 to 1.55 µm.…”

Section: Resultsmentioning

confidence: 99%

“…The laser beam was split into two beam paths: one was guided to a spintronic THz emitter (emission via the inverse spin-Hall effect) to generate a single-cycle linearly -polarised THz pulse in the system (See ref. 25 for details); the other, going through a TOPAS-OPA to allow wavelength tuning from 290 nm to 2.6 μm, was guided to the receiver to generate photocarriers. A schematic of the THz time-domain spectroscopy setup is presented in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Commercial fibre-coupled THz time-domain spectrometers have been recently released by a range of manufacturers. THz emitter and receiver technologies that are appropriate for operation with the 1–2 μm wavelength (telecom) band of fibre femtosecond lasers include spintronic THz emitters 23 – 25 , electro-optic polymer THz emitter-receiver pairs 26 , 27 and photoconductive antennas 28 . Amongst them, photoconductive antennas stand out for currently available commercial all-fibre THz systems owing to their simplicity, compactness, and ease of direct coupling to fibre optics.…”

Section: Introductionmentioning

confidence: 99%

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Direct and integrating sampling in terahertz receivers from wafer-scalable InAs nanowires

Peng,

Morgan,

Wagner

et al. 2024

Nat Commun

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Terahertz (THz) radiation will play a pivotal role in wireless communications, sensing, spectroscopy and imaging technologies in the decades to come. THz emitters and receivers should thus be simplified in their design and miniaturized to become a commodity. In this work we demonstrate scalable photoconductive THz receivers based on horizontally-grown InAs nanowires (NWs) embedded in a bow-tie antenna that work at room temperature. The NWs provide a short photoconductivity lifetime while conserving high electron mobility. The large surface-to-volume ratio also ensures low dark current and thus low thermal noise, compared to narrow-bandgap bulk devices. By engineering the NW morphology, the NWs exhibit greatly different photoconductivity lifetimes, enabling the receivers to detect THz photons via both direct and integrating sampling modes. The broadband NW receivers are compatible with gating lasers across the entire range of telecom wavelengths (1.2–1.6 μm) and thus are ideal for inexpensive all-optical fibre-based THz time-domain spectroscopy and imaging systems. The devices are deterministically positioned by lithography and thus scalable to the wafer scale, opening the path for a new generation of commercial THz receivers.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct and integrating sampling in terahertz receivers from wafer-scalable InAs nanowires

Peng,

Morgan,

Wagner

et al. 2024

Nat Commun

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“…In summary, the targeted doping of GaAs has produced a wide variety of dilute ferromagnetic semiconductors [8,11]. GaAs-based dilute magnetic semiconductors have strong potential to produce a new field of spintronics or spin photonics research where electron spin plays a major role [12][13][14][15]. For example, connecting molecular nanostructures with GaAs dilute semiconductor and ferromagnetic electrodes can offshoot a new form of molecular spintronics.…”

Section: Introductionmentioning

confidence: 99%

New value of old knowledge: sulphur-based GaAs surface passivation and potential GaAs application in molecular electronics and spintronics

Tyagi

2023

Mater. Res. Express

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GaAs is well known for its extremely high electron mobility and direct band gap. Owing to the technological advances in silicon-based technology, GaAs has been limited to niche areas. This paper discusses the application of GaAs in molecular electronics and spintronics as a potential field for considering this amazing but challenging material. GaAs is challenging because its surface is characterized by a high density of surface states, which precludes the utilization of this semiconducting material in mainstream devices. Sulfur(S)-based passivation has been found to be significantly useful for reducing the effect of dangling bonds and was researched thoroughly. GaAs applications in molecular spintronics and electronics can benefit significantly from prior knowledge of GaAs and S interactions because S is a popular functional group for bonding molecular device elements with different semiconductors and metals. In this article, the problem associated with the GaAs surface is discussed in a tutorial form. A wide variety of surface passivation methods has been briefly introduced. We attempted to highlight the significant differences in the S-GaAs interactions for different S passivation methods. We also elaborate on the mechanisms and atomic-scale understanding of the variation in surface chemistry and reconstruction due to various S passivation methods. It is envisioned that GaAs and thiol-terminated molecule-based novel devices can exhibit novel device characteristics and bring the added advantage of S-based passivation.

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Maximizing the Electromagnetic Efficiency of Spintronic Terahertz Emitters

Koleják,

Lezier,

Vala

et al. 2024

Advanced Photonics Research

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Optically pumped spintronic terahertz emitters (STEs) have, in less than a decade, strongly impacted terahertz (THz) source technology, by the combination of their Fourier‐limited ultrafast response, their phononless emission spectrum and their wavelength‐independent operation. However, the intrinsic strength of the inverse spin Hall effect governing these devices introduces a challenge: the optical‐to‐terahertz conversion efficiency is considerably lower than traditional sources. It is therefore primordial to maximize at least their electromagnetic efficiency independently of the spin dynamics at play. Using a rigorous time‐domain treatment of the electromagnetic generation and extraction processes, an optimized design is presented and experimentally confirmed. With respect to the strongest reported spintronic THz emitters it achieves a 250% enhancement of the emitted THz field and therefore an 8 dB increase of emitted power. This experimental achievement brings STE close to the symbolic barrier of mW levels. The design strategy is generically applicable to any kind of ultrafast spin‐to‐charge conversion (S2C) system. On a broader level, our work highlights how a rigorous handling of the purely electromagnetic aspects of THz spintronic devices can uncover overlooked aspects of their operation and lead to substantial improvements.

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Optimised Spintronic Emitters of Terahertz Radiation for Time-Domain Spectroscopy

Cited by 4 publications

References 28 publications

Direct and integrating sampling in terahertz receivers from wafer-scalable InAs nanowires

Direct and integrating sampling in terahertz receivers from wafer-scalable InAs nanowires

New value of old knowledge: sulphur-based GaAs surface passivation and potential GaAs application in molecular electronics and spintronics

Maximizing the Electromagnetic Efficiency of Spintronic Terahertz Emitters

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