High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures

Zhang, Liangliang; Mu, Kaijun; Zhou, Yichao; Wang, Hai; Zhang, Cunlin; Zhang, X.-C.

doi:10.1038/srep12536

Cited by 16 publications

(26 citation statements)

References 39 publications

(35 reference statements)

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“…Illumination of a metal surface with ultrashort laser pulses can result in the generation of terahertz radiation 1 . The generation efficiency can be enhanced by using metallic nanostructures 2 , such as gratings 3 , percolated films 4–7 , randomly arranged nanoparticles 8 , nanohole and nanoparticle ordered arrays 6,9 , and metasurfaces 10,11 . This is explained by the plasmonic enhancement of the optical fields.…”

Section: Introductionmentioning

confidence: 99%

“…Two main physical models have been proposed to explain terahertz generation from metal surfaces. Optical rectification, i.e., a second-order nonlinear optical process, is invoked as a mechanism of terahertz generation at relatively low pump intensities (<1 GW/cm 2 ) 1,4,6,7,11,13 . For high pump intensities (>1 GW/cm 2 ), terahertz generation is commonly explained by the ponderomotive acceleration of photoejected electrons 3,6,9,14 .…”

Section: Introductionmentioning

confidence: 99%

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Terahertz emission from gold nanorods irradiated by ultrashort laser pulses of different wavelengths

Takano

Asai

Kato

et al. 2019

Sci Rep

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Electron photoemission and ponderomotive acceleration by surface enhanced optical fields is considered as a plausible mechanism of terahertz radiation from metallic nanostructures under ultrafast laser excitation. To verify this mechanism, we studied experimentally terahertz emission from an array of gold nanorods illuminated by intense (~10–100 GW/cm 2 ) femtosecond pulses of different central wavelengths (600, 720, 800, and 1500 nm). We found for the first time that the order of the dependence of the terahertz fluence on the laser intensity is, unexpectedly, almost the same (~4.5–4.8) for 720, 800, and 1500 nm and somewhat higher (~6.6) for 600 nm. The results are explained by tunneling currents driven by plasmonically enhanced laser field. In particular, the pump-intensity dependence of the terahertz fluence is more consistent with terahertz emission from the sub-cycle bursts of the tunneling current rather than with the ponderomotive mechanism.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Terahertz emission from gold nanorods irradiated by ultrashort laser pulses of different wavelengths

Takano

Asai

Kato

et al. 2019

Sci Rep

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“…The so-called Large-Area Photoconductive antennas produce up to 1 mW of radiation power at best, but such devices are driven by a low repetition rate and high pulse power femtosecond lasers [ 7 , 8 ]. Further improvements in photoconductive antennas take advantage of the surface plasmon polariton phenomena [ 9 ] or the usage of the hybrid graphene molybdenum disulphide structure [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Silicon Field Effect Transistor as the Nonlinear Detector for Terahertz Autocorellators

Ikamas

Nevinskas

Krotkus

et al. 2018

Sensors

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We demonstrate that the rectifying field effect transistor, biased to the subthreshold regime, in a large signal regime exhibits a super-linear response to the incident terahertz (THz) power. This phenomenon can be exploited in a variety of experiments which exploit a nonlinear response, such as nonlinear autocorrelation measurements, for direct assessment of intrinsic response time using a pump-probe configuration or for indirect calibration of the oscillating voltage amplitude, which is delivered to the device. For these purposes, we employ a broadband bow-tie antenna coupled Si CMOS field-effect-transistor-based THz detector (TeraFET) in a nonlinear autocorrelation experiment performed with picoseconds-scale pulsed THz radiation. We have found that, in a wide range of gate bias (above the threshold voltage Vth=445 mV), the detected signal follows linearly to the emitted THz power. For gate bias below the threshold voltage (at 350 mV and below), the detected signal increases in a super-linear manner. A combination of these response regimes allows for performing nonlinear autocorrelation measurements with a single device and avoiding cryogenic cooling.

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“…Another promising material class for realizing THz sources are metals 30 because they exhibit a pump absorptivity largely independent of wavelength 31 , short electron lifetimes of ~10 to 50 fs 32 (implying broadband photocurrents), a featureless THz refractive index 33 (favoring gap-free emission) and a large heat conductivity (for efficient removal of excess heat). In addition, metal thin-film stacks (heterostructures) are well established, simple and cheap to fabricate.…”

Section: Introductionmentioning

confidence: 99%

Efficient metallic spintronic emitters of ultrabroadband terahertz radiation

Seifert¹,

Jaiswal²,

Martens³

et al. 2016

Nature Photon

669

802

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Terahertz electromagnetic radiation is extremely useful for numerous applications such as imaging and spectroscopy. Therefore, it is highly desirable to have an efficient table-top emitter covering the 1-to-30-THz window whilst being driven by a low-cost, low-power femtosecond laser oscillator. So far, all solid-state emitters solely exploit physics related to the electron charge and deliver emission spectra with substantial gaps. Here, we take advantage of the electron spin to realize a conceptually new terahertz source which relies on tailored fundamental spintronic and photonic phenomena in magnetic metal multilayers: ultrafast photo-induced spin currents, the inverse spin-Hall effect and a broadband Fabry-Pérot resonance. Guided by an analytical model, such spintronic route offers unique possibilities for systematic optimization. We find that a 5.8-nm-thick W/CoFeB/Pt trilayer generates ultrashort pulses fully covering the 1-to-30-THz range. Our novel source outperforms laser-oscillatordriven emitters such as ZnTe(110) crystals in terms of bandwidth, terahertz-field amplitude, flexibility, scalability and cost. IntroductionThe terahertz (THz) window, loosely defined as the frequency range from 0.3 to 30 THz in the electromagnetic spectrum, is located between the realms of electronics and optics 1,2 . As this region coincides with many fundamental resonances of materials, THz radiation enables very selective spectroscopic insights into all phases of matter with high temporal 3,4 and spatial 5,6,7,8 resolution. Consequently, numerous applications in basic research 3,4 , imaging 5 and quality control 8 have emerged.To fully exploit the potential of THz radiation, energy-efficient and low-cost sources of ultrashort THz pulses are required. Most broadband table-top emitters are driven by femtosecond laser pulses that generate the required THz charge current by appropriately mixing the various optical frequencies 9,10 . Sources made from solids usually consist of semiconducting or insulating structures with naturally or artificially broken inversion symmetry. When the incident photon energy is below the semiconductor band gap, optical rectification causes a charge displacement that follows the intensity envelope of the incident pump pulse 9,10,11,12,13,14,15,16,17 . For above-band-gap excitation, the response is dominated by a photocurrent 18,19,20,21,22,23,24 with a temporally step-like onset and, thus, generally smaller bandwidth than optical rectification 9 . Apart from rare exceptions 14 , however, most semiconductors used are polar 1,2,12,13,15,16,17,21,22 and strongly attenuate THz radiation around optical phonon resonances, thereby preventing emission in the so-called Reststrahlen band located between ~1 and 15 THz.The so far most promising sources covering the full THz window are photocurrents in transient gas plasmas 9,10,25,26,27,28,29 . The downside of this appealing approach is that the underlying ionization process usually requires amplified laser pulses with high threshold energies on the order of 0....

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High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures

Cited by 16 publications

References 39 publications

Terahertz emission from gold nanorods irradiated by ultrashort laser pulses of different wavelengths

Terahertz emission from gold nanorods irradiated by ultrashort laser pulses of different wavelengths

Silicon Field Effect Transistor as the Nonlinear Detector for Terahertz Autocorellators

Efficient metallic spintronic emitters of ultrabroadband terahertz radiation

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