Ultrabroadband single-cycle terahertz pulses with peak fields of 300 kV cm−1 from a metallic spintronic emitter

Seifert, Tom S.; Jaiswal, Samridh; Sajadi, Mohsen; Jakob, G.; Winnerl, Stephan; Wolf, Martin; Kläui, Mathias; Kampfrath, Tobias

doi:10.1063/1.4986755

Cited by 179 publications

(133 citation statements)

References 41 publications

(36 reference statements)

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“…For a first demonstration of this idea, the authors of ref. [118] Note that the THz field spectrum was gapless and spanned the entire range from 0.1 to 10 THz with respect to 10% of the peak spectral amplitude (Figure 20b). The emitter costs of ≈20 EUR were dominated by the substrate price, two orders of magnitude less than the current price of (110)-cut ZnTe windows of comparable diameter.…”

Section: Large-area Spintronic Thz Emittersmentioning

confidence: 99%

See 1 more Smart Citation

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

284

147

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reason for this interest relies on the fact that THz radiation can couple resonantly to numerous fundamental motions of ions, electrons, and electron spins in all phases of matter. For example, in solids, the THz range overlaps with the frequency of lattice vibrations (phonons), the collision rates of conduction electrons, the binding energy of bound electron-hole pairs (excitons), and the precession frequency of spin waves (magnons). Consequently, THz radiation, both continuous-wave and pulsed, has been used for characterization of and gaining insight into elementary processes in complex materials. The majority of these studies used relatively weak THz fields and, thus, probed the linear response of the material, without inducing notable material modifications.Only recently, however, completely new avenues in THz science were opened up by triggering nonlinear THz responses of materials. [3][4][5][6][7][8][9][10][11][12][13] Instead of using weak fields to primarily observe selected THz modes such as phonons or magnons, strong fields allow one to actively drive them to unprecedentedly large amplitudes, potentially thereby resulting in novel states of matter. [6,8,11] For example, simulations suggest that exciting matter with intense THz transients may lead to massive modifications of electrically [14] or magnetically [15] ordered domains and enable the acceleration of free ions to ≈1 MeV, [16] and postacceleration to 50-100 MeV energies. [17] Remarkable experimental results such as switching of magnetic order, [18,19] parametric amplification of optical phonons, [20] novel insights into spin-lattice coupling, [21,22] and acceleration of free electrons in a THz linear accelerator [23] were achieved only recently. This progress has been made possible by the development of laser-driven table-top THz sources routinely providing pulses with unprecedented energies and peak electric and magnetic field strengths throughout the entire THz spectral range. Different laser-based THz pulse generation techniques can be used to access different parts of the spectral range extending from 0.1 to 10 THz. Some of the recently developed technologies enable the generation of radiation with even larger bandwidth or tuning range up to 100 THz and beyond, which lead to an extension of what is called the THz spectral range. An overview of the approximate spectral coverage and the achieved highest pulse energies and peak electric-field strengths of various laserdriven technologies is given in Figure 1. ScopeIn this work, the basic principles of femtosecond-laser-driven intense pulsed THz sources and their recent development are reviewed. These sources are capable of delivering peak electric field strengths on the MV cm −1 scale. Corresponding typical THz pulse energies are on the µJ-to-mJ level, depending on A review on the recent development of intense laser-driven terahertz (THz) sources is provided here. The technologies discussed include various types of sources based on optical rectification (OR), spintronic emitters, and laserfilame...

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Section: Large-area Spintronic Thz Emittersmentioning

confidence: 99%

“…[118] grew W(1.8 nm)|Co 40 Fe 40 B 20 (2 nm) |Pt(1.8 nm) trilayers on a glass substrate with a diameter of 7.5 cm. Therefore, this emitter concept is easily scalable, making it interesting as a THz source for broadband nonlinear THz spectroscopy.…”

Section: Large-area Spintronic Thz Emittersmentioning

confidence: 99%

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

284

147

View full text Add to dashboard Cite

show abstract

“…In 2013, Kampfrath et al utilized the ultrathin ferromagnetic/nonmagnetic (NM/FM) heterostructures as an efficient THz radiation source . The spintronic‐based THz emitters have been optimized with respect to layer thickness, growth parameters, substrates, and enhanced absorption rate . Especially, using both forward and backward spin currents, Kampfrath and co‐workers optimized the spintronic structure and further improved THz radiation with peak fields of several 100 kV cm −1 .…”

mentioning

confidence: 99%

“…Especially, using both forward and backward spin currents, Kampfrath and co‐workers optimized the spintronic structure and further improved THz radiation with peak fields of several 100 kV cm −1 . Recently, the peak field of THz pulse (230 fs, 1–10 THz) has been demonstrated to be 300 kV cm −1 . The efficiency of THz generation is wavelength‐independent in the range of 900–1500 nm, which means that the details of the involved optical transitions are insignificant .…”

mentioning

confidence: 99%

Terahertz Radiation Modulated by Confinement of Picosecond Current Based on Patterned Ferromagnetic Heterostructures

Jin

Zhang

Zhu

et al. 2019

Physica Rapid Research Ltrs

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The ultrashort laser excitation of nonmagnetic/ferromagnetic/nonmagnetic (NM/FM/NM) heterostructures is intensively studied as a terahertz (THz) emitter. Herein, the combined spintronic and photonic ultrathin metal heterostructures are exploited to realize actively modulated THz radiation. It is demonstrated that the THz radiation can be mediated coherently through the charge current induced by the inverse spin Hall effect (ISHE) and the built‐in transient current quasi‐simultaneously created within the striped NM/FM/NM heterostructures. The waveforms of THz radiation can be shaped by the charge current confinement effect, including the amplitude modulation and the center‐frequency shift. These findings can be utilized for device‐oriented opto‐spintronics and also extend the established THz emitter to THz modulator.

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“…Due to the presence of high frequency components, the THz beam can be focused to a very small spot size, which can induce giant THz peak electric fields of up to 8 MV cm −1 for a peak power of 12 MW [14]. Today, more options are studied for the generation of intense THz pulses, such as the spintronic and liquid emitters [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Intense sub-terahertz radiation from wide-bandgap semiconductor based large-aperture photoconductive antennas pumped by UV lasers

et al. 2019

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The characteristics of terahertz (THz) radiation generated from large-aperture photoconductive antennas (LAPCAs) were investigated. The antennas were fabricated using different wide-bandgap semiconductor crystals (ZnSe, GaN, 6H-SiC, 4H-SiC and β-Ga 2 O 3 ) as the substrate. We used an amplified sub-picosecond KrF excimer laser for illumination of the LAPCAs. THz emission scaling was studied as a function of the bias field and the pump laser energy. It was found that the radiated THz energy scales quadratically as a function of the bias field and sub-linearly as a function of the optical fluence for most of the substrates. Further, we demonstrate that SiC, and especially 4H-SiC LAPCAs offer the best THz generation performances. In order to generate intense THz radiation, we fabricated both 6H-and 4H-SiC LAPCAs with an interdigitated structure. From the field autocorrelation trace, it was found that the spectra lie in the sub-THz regime, extending up to 400 GHz, with a peak frequency at 50 GHz, making the bridge between the microwaves band and the THz band. The maximum generated THz energy was 11 μJ, which is to date the highest THz energy measured from LAPCA sources, with a corresponding peak electric field of 115 kV cm −1 and a corresponding ponderomotive potential of 60 eV. Nonlinear THz experiments were performed using these energetic THz pulses, and open aperture Z-scan experiments in an n-doped InGaAs layer revealed a transmission enhancement of 1.7. It was also shown that in order to have efficient THz generation, the energy contrast of the laser must be kept high.

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Ultrabroadband single-cycle terahertz pulses with peak fields of 300 kV cm−1 from a metallic spintronic emitter

Cited by 179 publications

References 41 publications

Laser‐Driven Strong‐Field Terahertz Sources

Laser‐Driven Strong‐Field Terahertz Sources

Terahertz Radiation Modulated by Confinement of Picosecond Current Based on Patterned Ferromagnetic Heterostructures

Intense sub-terahertz radiation from wide-bandgap semiconductor based large-aperture photoconductive antennas pumped by UV lasers

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