Air nonlinear dynamics initiated by ultra-intense lambda-cubic terahertz pulses

Shalaby, Mostafa; Hauri, Christoph P.

doi:10.1063/1.4919876

Cited by 28 publications

(12 citation statements)

References 35 publications

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“…The pump-probe scheme enables us, in addition, to visualize the off-equilibrium evolution of these excitations at a subpicosecond time scale [1][2][3][4][5][6][7][8][9][10]. The very recent advent of ultrastrong THz fields up to 83 MV=cm and 28 Tesla [9,10] is considered the forthcoming mean to precisely control electronic and magnetic ultrafast dynamics, to drive novel highly nonlinear processes in condensed matter, to accelerate electron to relativistic energy [11][12][13][14][15][16][17][18][19], and to prepare quasistationary states in solids. So far, a THz-driven nonlinear χ ð2Þ process has been demonstrated in ZnTe to induce crossphase modulation (XPM) and spectral broadening on a laser pulse.…”

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confidence: 99%

Subcycle Extreme Nonlinearities in GaP Induced by an Ultrastrong Terahertz Field

2017

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We report on the experimental observation of extreme laser spectral broadening and a change in optical transmission in gallium phosphite induced by 25 MV/cm terahertz (THz) single-cycle internal field. Such intense THz radiation leads to twofold transient modifications of the optical properties in the electro-optical crystal. First, the electric field provokes extensive cross-phase modulation via the χ^{(2)} and χ^{(3)} nonlinearities on a copropagating 50 fs near infrared laser pulse which turns into 500% spectral broadening. Second, we observe an instantaneous change of the optical transmission occurring at the THz field which is alleged to interband Zener tunneling and charge carrier density modification by impact ionization turning the semiconductor in a metal-like transient state. The presented scheme displays a pathway to coherently control the optical properties of semiconductors on an ultrafast time scale by a strong THz field.

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confidence: 99%

Subcycle Extreme Nonlinearities in GaP Induced by an Ultrastrong Terahertz Field

2017

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“…The generated radiation spans frequencies between 0.2 and 3 THz. We measured the damage threshold as well as the dependency of the conversion efficiency on the pump fluence, pump wavelength, and pulse duration.High field terahertz (0.1-10 THz) generation is a topic of numerous ongoing researches due to its wide range of science applications [1][2][3][4][5][6][7][8][9][10][11]. Presently, optical rectification (OR) in nonlinear crystals is the preferred generation technique as it allows the realization of the most intense THz source.…”

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confidence: 99%

Intense THz source based on BNA organic crystal pumped at Ti:sapphire wavelength

et al. 2016

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We report on high energy terahertz pulses by optical rectification (OR) in the organic crystal N-benzyl-2-methyl-4-nitroaniline (BNA) directly pumped by a conventional Ti:Sapphire (Ti:Sa) amplifier. The simple scheme provides an optical to terahertz conversion efficiency of 0.25% when pumped by a collimated laser pulses with duration of 50 fs and central wavelength of 800nm. The generated radiation spans frequencies between 0.2 and 3 THz. We measured the damage threshold as well as the dependency of the conversion efficiency on the pump fluence, pump wavelength, and pulse duration.High field terahertz (0.1-10 THz) generation is a topic of numerous ongoing researches due to its wide range of science applications [1][2][3][4][5][6][7][8][9][10][11]. Presently, optical rectification (OR) in nonlinear crystals is the preferred generation technique as it allows the realization of the most intense THz source. The figures of merit of a high-field THz source are the pump-to-THz conversion efficiency, THz spectrum, focusability and the applicable pump wavelength. The wide use of Ti:Sa laser technology in ultrafast THz spectroscopy has inspired the development of a THz emitter which can be pumped directly by those powerful lasers. Presently, for the most intense THz sources Ti:Sapphire needs to be converted to the short wavelength midinfrared spectral range to provide efficient phase-matching [11][12][13][14].In this letter, we report on THz generation in the organic crystal BNA which is pumped at the Ti:Sa 800 nm wavelength. The conversion efficiency and spectral density offered by BNA surpasses other organic crystals pumped at conventional Ti:Sa wavelength in the range of 0.1-3 THz by a factor 10-100. It thus represents a valuable option to the widely used Ti:Sa pumped Lithium Niobate (LN) crystal as the generation scheme is simpler and does not require pulse front tilting.Among all nonlinear crystals, LN [10] and organic crystals (DAST, DSTMS, OH1) [11][12][13][14][15] provide most efficient OR. The typical conversion efficiency for LN pumped at 800 nm [10] and 1030 nm reaches 0.1-0.2 % that can thus be further increased by a factor of three by cryo-cooling the LN [15,16]. However, the reported conversion efficiency is still debated as other research groups [15,16] who repeated the experiment obtained conversion efficiency smaller by an order of magnitude than ref. [17,18]. Due to the notorious focusing issues of LN, which are partly caused by the asymmetric beam quality and the complex geometry, the maximum reported THz field strength has not surpassed 1 MV/cm [10]. LN-based sources emit in the low-THz range (0.1-3 THz). Until now, this range has been difficult to access by organic crystals.Organic crystals offer excellent phase-matching for OR in a simple pump beam configuration and superior THz focusability. The high 2-3% conversion efficiency is achieved for a pump wavelength between 1.2-1.5 µm [11,13]. Such a scheme allows for extreme focusing peak fields reaching up to 83 MV/cm [11]. Yet, the main drawback of or...

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“…This value agrees reasonably with the estimated peak field (51 MV/cm) from our independent calibration 10 using the spot size, THz energy, and time trace as well as a corresponding measurement of air nonlinearity. 15 The polarization switching scheme presented here thus offers three orders of magnitude larger phase retardation than what has been provided by the state-of-the-art THz sources in the past. 14 In this configuration, the transmitted energy of the nIR pulse behind the crossed polarizer is measured to be as high as 90%, demonstrating the efficiency of this pulse picking system.…”

Section: Resultsmentioning

confidence: 92%

“…Even though the Kerr coefficient is weaker than in many other media such as liquid, 18 air, 15 and solids, 19,20 diamond has three main advantages for the realization of an ultrafast THz Kerr gate. First, diamond is an insulator with a wide bandgap (E gap = 5.5 eV) which reduces the probability of electron-hole pair generation across the bandgap upon nonlinear excitation.…”

Section: Resultsmentioning

confidence: 99%

Extreme nonlinear terahertz electro-optics in diamond for ultrafast pulse switching

2017

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Polarization switching of picosecond laser pulses is a fundamental concept in signal processing [C. Chen and G. Liu, Annu. Rev. Mater. Sci. 16, 203 (1986); V. R. Almeida et al., Nature 431, 1081 (2004); and A. A. P. Pohl et al., Photonics Sens. 3, 1 (2013)]. Conventional switching devices rely on the electro-optical Pockels effect and work at radio frequencies. The ensuing gating time of several nanoseconds is a bottleneck for faster switches which is set by the performance of state-of-the-art high-voltage electronics. Here we show that by substituting the electric field of several kV/cm provided by modern electronics by the MV/cm field of a single-cycle THz laser pulse, the electro-optical gating process can be driven orders of magnitude faster, at THz frequencies. In this context, we introduce diamond as an exceptional electro-optical material and demonstrate a pulse gating time as fast as 100 fs using sub-cycle THz-induced Kerr nonlinearity. We show that THz-induced switching in the insulator diamond is fully governed by the THz pulse shape. The presented THz-based electro-optical approach overcomes the bandwidth and switching speed limits of conventional MHz/GHz electronics and establishes the ultrafast electro-optical gating technology for the first time in the THz frequency range. We finally show that the presented THz polarization gating technique is applicable for advanced beam diagnostics. As a first example, we demonstrate tomographic reconstruction of a THz pulse in three dimensions.

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Air nonlinear dynamics initiated by ultra-intense lambda-cubic terahertz pulses

Cited by 28 publications

References 35 publications

Subcycle Extreme Nonlinearities in GaP Induced by an Ultrastrong Terahertz Field

Subcycle Extreme Nonlinearities in GaP Induced by an Ultrastrong Terahertz Field

Intense THz source based on BNA organic crystal pumped at Ti:sapphire wavelength

Extreme nonlinear terahertz electro-optics in diamond for ultrafast pulse switching

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