Transient birefringence of liquids induced by terahertz electric-field torque on permanent molecular dipoles

Sajadi, Mohsen; Wolf, Martin; Kampfrath, Tobias

doi:10.1038/ncomms14963

Cited by 69 publications

(95 citation statements)

References 47 publications

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“…[165,166] By comparing optically driven with THz-driven alignment, it was determined whether or whether not rotational molecular degrees of freedom make a dominant contribution to the dielectric function of polar solvents such as methanol. Accordingly, it was shown that intense THz pulses align solvent molecules more efficiently than optical fields do.…”

Section: Properties Of Driven Modesmentioning

confidence: 99%

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

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287

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: Properties Of Driven Modesmentioning

confidence: 99%

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

Self Cite

287

147

View full text Add to dashboard Cite

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“…To provide a first demonstration of the capability of these pulses for THz nonlinear optics, we measure the THz Kerr effect 31,32,34,33 of diamond. To study this ( ) -type nonlinear optical effect, the p-polarized THz transient is focused into a 320 μm thick polycrystalline diamond crystal.…”

mentioning

confidence: 99%

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

Seifert

Jaiswal

Sajadi

et al. 2017

Applied Physics Letters

179

128

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To explore the capabilities of metallic spintronic thin-film stacks as a source of intense and broadband terahertz electromagnetic fields, we excite a W/CoFeB/Pt trilayer on a large-area glass substrate (diameter of 7.5 cm) by a femtosecond laser pulse (energy 5.5 mJ, duration 40 fs, wavelength 800 nm). After focusing, the emitted terahertz pulse is measured to have a duration of 230 fs, a peak field of 300 kV cm -1 and an energy of 5 nJ. In particular, the waveform exhibits a gapless spectrum extending from 1 to 10 THz at 10% of amplitude maximum, thereby facilitating nonlinear control over matter in this difficult-to-reach frequency range and on the sub-picosecond time scale.Terahertz (THz) pulses covering the range from 1 to 20 THz are useful resonant probes of numerous low-energy excitations in all phases of matter. Completely new research avenues open up when THz pulses are used to drive rather than probe materials resonances.

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“…OR typically allows us to generate intense THz radiation below 5 THz (sketched in light green and light red in Figure 1c), while DFG covers higher frequencies (dark green and dark red in Figure 1c). Both inorganic (LiNbO 3 [66][67][68][69][70][71][72][73][74][75][76][77], GaSe [78][79][80], ZnTe [81,82], LiGaS 2 [83], GaP [84][85][86][87][88][89]) as well as organic (DSTMS [89][90][91][92], OH1 [93][94][95][96][97], DAST [98,99], DPFO [100], HMQ-TMS [101], OHQ-N2S [102]) crystals are phase-matched in the NIR and can emit pulsed THz fields with peak amplitudes in excess of 1 MV/cm. The approximate spectrum of the strongest THz pulses generated to date by non-linear optical methods in inorganic [62,64] and organic [63,65] crystals are shown in green and in red in Figure 1c, respectively.…”

Section: Introductionmentioning

confidence: 99%

Towards Intense THz Spectroscopy on Water: Characterization of Optical Rectification by GaP, OH1, and DSTMS at OPA Wavelengths

2020

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Water is the most prominent solvent. The unique properties of water are rooted in the dynamical hydrogen-bonded network. While TeraHertz (THz) radiation can probe directly the collective molecular network, several open issues remain about the interpretation of these highly anharmonic, coupled bands. In order to address this problem, we need intense THz radiation able to drive the liquid into the nonlinear response regime. Firstly, in this study, we summarize the available brilliant THz sources and compare their emission properties. Secondly, we characterize the THz emission by Gallium Phosphide (GaP), 2–{3–(4–hydroxystyryl)–5,5–dimethylcyclohex–2–enylidene}malononitrile (OH1), and 4–N,N–dimethylamino–4′–N′–methyl–stilbazolium 2,4,6–trimethylbenzenesulfonate (DSTMS) crystals pumped by an amplified near-infrared (NIR) laser with tunable wavelength. We found that both OH1 as well as DSTMS could convert NIR laser radiation between 1200 and 2500 nm into THz radiation with high efficiency (> 2 × 10−4), resulting in THz peak fields exceeding 0.1 MV/cm for modest pump excitation (~ mJ/cm2). DSTMS emits the broadest spectrum, covering the entire bandwidth of our detector from ca. 0.5 to ~7 THz, also at a laser wavelength of 2100 nm. Future improvements will require handling the photothermal damage of these delicate organic crystals, and increasing the THz frequency.

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Transient birefringence of liquids induced by terahertz electric-field torque on permanent molecular dipoles

Cited by 69 publications

References 47 publications

Laser‐Driven Strong‐Field Terahertz Sources

Laser‐Driven Strong‐Field Terahertz Sources

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

Towards Intense THz Spectroscopy on Water: Characterization of Optical Rectification by GaP, OH1, and DSTMS at OPA Wavelengths

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