Single-cycle multiterahertz transients with peak fields above 10 MV/cm

Junginger, F.; Sell, Alexander; Schubert, Olaf; Mayer, Bernhard; Brida, Daniele; Marangoni, Marco; Cerullo, Giulio; Leitenstorfer, Alfred; Huber, Rupert

doi:10.1364/ol.35.002645

Cited by 174 publications

(123 citation statements)

References 24 publications

(44 reference statements)

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“…We refer to the former situation as "low-inertia" sources of nonlinearity, and to the latter as "high-inertia" sources. For the case of ultrashort optical pulses, including intense picosecond terahertz pulses [4][5][6][7][8][9], the dominant source of nonlinearity tends to be the low-inertia, single-particle sources [13]. For the pulses in the visible and near IR spectral ranges, the dominant low-inertia mechanism of nonlinearity is electronic [12][13][14].…”

Section: The Vibrational Contribution To the Nonlinear Refractivementioning

confidence: 99%

“…Since their first demonstrations, terahertz techniques continue to find new applications from medical diagnostics and therapy to the detection of hidden substances, including explosives and drugs [1][2][3]. In recent years, pulsed sources of the terahertz radiation with sufficient intensity for the observation of nonlinear optical effects have appeared in a number of laboratories [4][5][6][7][8][9]. Investigation of the nonlinear optical effects in the terahertz spectral range has now become feasible [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Prediction of an extremely large nonlinear refractive index for crystals at terahertz frequencies

et al. 2015

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We develop a simple analytical model for calculating the vibrational contribution to the nonlinear refractive index n2 (Kerr coefficient) of a crystal in terms of known crystalline parameters such as the linear refractive index, the coefficient of thermal expansion, atomic density, and the reduced mass and the natural oscillation frequency of the vibrational modes of the crystal lattice. We show that the value of this contribution in the terahertz spectral region can exceed the value of the nonlinear refractive index n2 in the visible and near-IR spectral ranges (which is largely electronic in origin) by several orders of magnitude. For example, for crystal quartz the value of the Kerr coefficient in the low-frequency limit is n2 = 2.2 × 10 −9 esu or equivalently is 4.4 × 10 −16 m 2 /W, which is very much larger than its value of 3 × 10 −20 m 2 /W in the visible range. Furthermore, we present an analysis of the dispersion of n2 in the terahertz spectral range and show that even larger values of n2 occur for frequencies close to the vibrational resonances.

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Section: The Vibrational Contribution To the Nonlinear Refractivementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prediction of an extremely large nonlinear refractive index for crystals at terahertz frequencies

et al. 2015

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“…The characterization relies on EOS in 19 μm thick ZnTe with gating pulses that are shorter than 10 fs to ensure the precise detection of frequencies up to 40 THz [29]. The birefringent refractive index can be described with two distinct Sellmeier equations separated by the reststrahlen band for the near infrared [obtained by Wang et al [18] and Fig.…”

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confidence: 99%

Coherent Field Transients below 15 THz from Phase-Matched Difference Frequency Generation in 4H-SiC

Fischer

Bühler

Kurihara

et al. 2017

Conference on Lasers and Electro-Optics

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We experimentally demonstrate tunable, phase-matched difference frequency generation covering the spectral region below 15 THz using 4H-SiC as a nonlinear crystal. This material combines a non-centrosymmetric lattice and strong birefringence with broadband transparency at low optical frequencies. Thorough refractive index measurements in the terahertz spectral range allow us to calculate phase-matching conditions for any near-infrared pump laser source. 4H-SiC is also exploited as a detector crystal for electro-optic sampling. The results allow us to estimate the effective second-order nonlinear coefficient. The generation of coherent radiation in the spectral region between 5 and 15 THz is a major challenge for solid-state sources, despite its relevant interest for the study of fundamental excitations in condensed matter systems. In fact, the corresponding energy range from 20 to 60 meV includes various molecular vibrations [1][2][3], as well as optical phonons in solids [4,5] and low-energy collective modes in correlated materials such as superconductors [6]. Quantum cascade lasers [7] provide a continuous wave source tunable in this spectral window. Pulses can also be produced by photoconductive switches [8,9] or via laser-induced air plasma generation [10][11][12]. However, to obtain stable and intense electric fields combined with femtosecond temporal resolution, the workhorse approach relies on the generation of coherent field transients by frequency mixing processes in nonlinear crystals [13,14]. A typical setup is based on difference frequency generation (DFG) driven by an ultrafast laser system. Unfortunately, in the elusive spectral region between 5 and 15 THz, most nonlinear crystals applied for DFG such as GaSe, AgGaS 2 (AGS), and BBO, exhibit strong optical phonon resonances that lead to reststrahlen bands where radiation cannot penetrate into the material [see Fig. 1(a)]. In addition, isotropic materials such as ZnTe are lacking birefringence and, therefore, do not allow adjustment of phase matching. Furthermore, organic nonlinear crystals [15] show heavily structured spectra in the frequency range of interest and display inherently low damage thresholds. Recently, preliminary investigations by Naftaly et al.[16] suggested 4H-SiC as a crystal suitable for nonlinear optics in the multi-terahertz range. So far, this outstanding material has received little attention in experimental works that are limited to the demonstration of nonlinear properties in the near infrared [17], mid-infrared DFG above the optical phonon frequencies [18], and emission of 1 THz radiation from 6H-SiC [19].In this Letter, we experimentally demonstrate the application of 4H-SiC for the generation of ultrashort field transients tunable between 5 and 15 THz, and its use as an electro-optic sampling (EOS) crystal.SiC exhibits a large plurality of polymorphs with hexagonal, cubic, and rhombohedral symmetry [20]. Owing to its technological relevance, high-quality synthetic crystals of 4H-SiC are available. Its lattice, sketched in...

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“…[4][5][6][7] While laser-based THz radiation at frequencies 20-100 THz has been generated by difference frequency mixing in nonlinear inorganic crystals, 8 the generation of highpower THz single-cycle pulses above 1 MV/cm in the range of 0.1-10 THz, the so-called THz gap, is still challenging due to the limited availability of appropriate THz emitters. 9 Only recently, single-cycle pulses at 0.8 THz central frequency of 1 MV/cm have been demonstrated by optical rectification (OR) in LiNbO 3 (Ref.…”

mentioning

confidence: 99%

Strong-field single-cycle THz pulses generated in an organic crystal

Hauri

Ruchert

Vicario

et al. 2011

Applied Physics Letters

203

133

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We present high-power single-cycle carrier-envelope phase locked THz pulses at a central frequency of 2.1 THz with MV/cm electric field strengths and magnetic field strengths beyond 0.3 T. The THz radiation is generated by optical rectification in an organic salt crystal 4-N,N-dimethylamino-4′-N′-methyl stilbazolium tosylate called DAST pumped with the signal wavelength of a powerful optical parametric amplifier. Conversion efficiencies of more than 2% are reported.

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Single-cycle multiterahertz transients with peak fields above 10 MV/cm

Cited by 174 publications

References 24 publications

Prediction of an extremely large nonlinear refractive index for crystals at terahertz frequencies

Prediction of an extremely large nonlinear refractive index for crystals at terahertz frequencies

Coherent Field Transients below 15 THz from Phase-Matched Difference Frequency Generation in 4H-SiC

Strong-field single-cycle THz pulses generated in an organic crystal

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