Multimillijoule coherent terahertz bursts from picosecond laser-irradiated metal foils

Liao, Guoqian; Li, Yutong; Liu, Hao; Scott, Graeme; Neely, D.; Zhang, Yihang; Zhu, Baojun; Zhang, Zhe; Armstrong, Chris; Zemaityte, Egle; Bradford, P.; Huggard, P. G.; Rusby, Dean; McKenna, P.; Brenner, C. M.; Woolsey, N. C.; Wang, Weimin; Sheng, Zheng-Ming; Zhang, Jie

doi:10.1073/pnas.1815256116

Cited by 107 publications

(73 citation statements)

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“…This length corresponds to a fundamental-to-SH relative phase shift of ϑ(L eff ) − ϑ 0 = π. [158] The strong THz emission is attributed to coherent transition radiation, induced by the laser-accelerated energetic electron bunch escaping the target. At off-axis angles, phase matching over much larger distances can be fulfilled, resulting in the conical emission pattern with typical opening angles in the range of 2° to 10°.…”

Section: Thz Sources Based On Laser-filament-induced Plasmasmentioning

confidence: 99%

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: Thz Sources Based On Laser-filament-induced Plasmasmentioning

confidence: 99%

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

284

147

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“…13 EMP in the THz domain is generated from electron oscillations in the target and is characterized by the duration of electron ejection. [14][15][16] Simultaneously, electromagnetic fields propagating through an interaction chamber will activate all the metallic parts, emitting EMP at lower frequencies (∼ 100 MHz) as chamber proper modes. a) Present address: CEA, DAM, DIF, F-91297 Arpajon Cedex, France.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic pulse emission from target holders during short-pulse laser interactions

et al. 2020

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For the first time, a global model of electromagnetic pulse (EMP) emission connects charge separation in the laser target to quantitative measurements of the electromagnetic field. We present a frequency-domain dipole antenna model which predicts the quantity of charge accumulated in a laser target as well as the EMP amplitude and frequency. The model is validated against measurements from several high-intensity laser facilities, providing insight into target physics and informing the design of next-generation ultra-intense laser facilities. EMP amplitude is proportional to the total charge accumulated on the target, but we demonstrate that it is not directly affected by target charging time (and therefore the laser pulse duration) provided the charging time is shorter than the antenna characteristic time. We propose two independent methods for estimating the charging time based on the laser pulse duration. We also investigate the impact of target holder geometry on EMPs using cylindrical, conical and helical holders. Published as: Minenna et al., Phys. Plasmas, 27, 063102 (2020), https://doi.

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“…Record values were later achieved in numerical simulations from which CTR took over PIR by delivering conversion efficiencies > 5 × 10 −3 and mJ THz pulse energies [15]. Such performances have been reached in laser-solid experiments [16,17].Besides, mid-and far-infrared light sources supplying TW peak powers are today available. Femtosecond laser facilities with 3.9 µm central wavelength opened the way to multi-octave supercontinuum generation [18] and can accelerate electrons to 12 MeV energy in gas jets [19].…”

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THz Generation from Relativistic Plasmas Driven by Near- to Far-Infrared Laser Pulses

2019

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Terahertz pulse generation by ultra-intense two-color laser fields ionizing gases with near-to farinfrared carrier wavelength is studied from particle-in-cell (PIC) simulations. For long wavelength (10.6 µm) promoting a large ratio of electron density over critical, photoionization is shown to catastrophically enhance the plasma wakefield, causing a net downshift in the optical spectrum and exciting THz fields with tens of GV/m amplitude in the laser direction. This emission is accompanied by coherent transition radiation (CTR) of comparable amplitude due to wakefield-driven electron acceleration. We analytically evaluate the fraction of CTR energy up to 30 % of the total radiated emission including the particle self-field and numerically calibrate the efficiency of the matched blowout regime for electron densities varied over three orders of magnitude. PACS numbers: 52.25.Os,42.65.Re,52.38.Hb The ability of terahertz (THz) waves to probe matter is attracting interest for lots of applications reviewed, e.g., in [1]. Recently, novel challenges such as compact THz electron accelerators [2][3][4] or THz-triggered chemistry [5] raised the need of mJ THz pulses with high field strength > GV/m. Optical rectification in organic crystals [6] or using tilted-pulse-front pumping [7] can achieve percent conversion efficiency and sub-mJ THz energies with few 0.1 GV/m field strengths. These solid-based technologies, however, remain limited by damage thresholds. In contrast, gas plasmas created by intense, two-color laser pulses may supply suitable emitters free of any damage [8]. Electrons are tunnel-ionized by the asymmetric light field usually composed of a near-IR fundamental wavelength (800 nm) and its second harmonic (400 nm). Their "photocurrent" polarized in the laser direction generates a broadband photocurrent-induced radiation (PIR) in the THz range [9]. Nevertheless, two-color setups using moderate intensities ∼ 10 14 W/cm 2 only achieve conversion efficiencies < 10 −3 and µJ energies [10,11].In the relativistic regime, however, when the normalized vector potential a 0 ≡ 8.5×10 −10 I 1/2 0 [W/cm 2 ]λ 0 [µm] is larger than unity (I 0 is the intensity and λ 0 denotes the laser wavelength), plasma waves trigger a strong longitudinal field exploited for laser-wakefield acceleration (LWFA) [12]. Accelerated electrons crossing the plasmavacuum interface can then emit coherent transition radiation (CTR) operating in the THz band. Leemans et al. [13,14] reported THz energy of 3-5 nJ per pulse measured from a dense gas jet of helium. Theoretical estimates assuming a Boltzmann distribution of 4.6 MeV confirmed this energy yield and anticipated the possibility to provide few 100 µJ energies by increasing the electron bunch to tens of MeV and/or the plasma diameter to mm scales. Record values were later achieved in numerical simulations from which CTR took over PIR by delivering conversion efficiencies > 5 × 10 −3 and mJ THz pulse energies [15]. Such performances have been reached in laser-solid experiments [16,17].Besides...

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Multimillijoule coherent terahertz bursts from picosecond laser-irradiated metal foils

Cited by 107 publications

References 51 publications

Laser‐Driven Strong‐Field Terahertz Sources

Laser‐Driven Strong‐Field Terahertz Sources

Electromagnetic pulse emission from target holders during short-pulse laser interactions

THz Generation from Relativistic Plasmas Driven by Near- to Far-Infrared Laser Pulses

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