Abstract

We show that the organic electro-optic crystal HMQ-TMS [2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 2,4,6-trimethylbenzenesulfonate] has favorable properties for the parametric generation of THz waves in a collinear type-0 phase-matching scheme, i.e., a low absorption coefficient at wavelengths from 800 to 1500 nm (α < 1.5cm−1), a relatively low absorption coefficient at frequencies from 0.3 to 1.5 THz (α < 100 cm−1), and a large coherence length in these spectral ranges (lc > 0.5 mm). We demonstrate efficient generation of broadband THz pulses through optical rectification of sub-picosecond laser pulses in a 0.2 mm thick HMQ-TMS crystal at the wavelength of 1000 nm. The energy conversion efficiency achieved in this crystal was 41 times higher than the one achieved in a 0.3 mm thick GaP crystal, which is an often used material for collinearly phase-matched THz generation at this laser wavelength. The peak amplitudes of the THz signal obtained with the HMQ-TMS crystal were 5.4 times larger in the time-domain and 7.1 times larger in the frequency-domain than the ones obtained with the GaP crystal.

© 2014 Optical Society of America

1. Introduction

Optical rectification of femtosecond laser pulses in an electro-optic crystal is an often used method for the generation of broadband THz pulses [1]. A high conversion efficiency in this process is crucial for both THz imaging and spectroscopy applications, because it leads to a high signal-to-noise ratio and can enable nonlinear optics experiments relying on intense THz pulses. It requires a crystal with a high transparency in the near-infrared (NIR) and THz spectral range and a high nonlinear optical susceptibility tensor element which can be exploited in a phase-matching scheme. For instance, collinear type-0 phase-matching is fulfilled in the inorganic electro-optic semiconductors ZnTe, GaP, and CdTe at the wavelengths of two of the most important femtosecond laser systems, namely 800 nm (Ti:sapphire lasers) and 1 μm (Yb-doped fiber lasers), respectively [24]. However, small energy conversion efficiencies of typically 3 × 10−5 are achieved in these materials [5, 6]. Up to two orders of magnitude higher conversion efficiencies can be obtained in some inorganic ferroelectric and organic molecular crystals with much higher optical nonlinearities. A conversion efficiency of 3.8 % was demonstrated in the inorganic ferroelectric crystal LiNbO3 at a laser wavelength of 1 μm, however, a more sophisticated Cherenkov phase-matching scheme and cryogenic cooling was required and the bandwidth of the generated THz pulses was relatively small [7]. Broadband THz pulses can be generated at room temperature in the organic crystals DAST (4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate), DSTMS (4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate), and OH1 {2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile} with conversion efficiencies up to 2 % at laser wavelengths between 1.3 μm and 1.5 μm [812]. The organic crystals COANP (2-cyclooctylamino-5-nitropyridine), HMQ-T [2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 4-methylbenzenesulfonate], and HMQ-TMS [2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 2,4,6-trimethylbenzenesulfonate] were shown to emit more intense THz pulses than ZnTe when pumped with a femtosecond Ti:sapphire laser or with the second harmonic of an ultrafast Er-doped fiber laser [1315].

In this paper, we report on the linear optical properties of the HMQ-TMS crystal for light polarized along its polar axis in the visible and infrared spectral range from 600 to 2000 nm and in the THz spectral range from 0.3 to 1.5 THz, discuss the phase-matching characteristics at various laser wavelengths based on this information and demonstrate efficient THz generation pumped at 1000 nm.

2. Basic properties

In the following, we will summarize some basic properties of HMQ-TMS crystals, which are of interest for nonlinear optical applications [14]. The HMQ-TMS crystal is an organic molecular salt crystal built up of HMQ [2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium] cations with virtually perfect parallel alignment and TMS (2,4,6-trimethylbenzenesulfonate) counter anions. It belongs to the monoclinic point group m. The polar axis is oriented along the dielectric x3 direction. Large area plane parallel slabs containing the polar axis can be prepared by cleaving as-grown crystals along the crystallographic ac-plane. The HMQ molecule shows an effective first-order hyperpolarizability obtained by quantum chemical calculation of β333eff=185×1030esu, which is larger than the ones of OH1 ( β333eff=63×1030esu) and DAST ( β111eff=161×1030esu) [14, 16]. Since the HMQ-TMS and DAST crystals have similar structures and microscopic nonlinearities, it can be expected that the largest electro-optic coefficient of the HMQ-TMS crystal is comparable to the one of the DAST crystal, which is about one order of magnitude larger than the ones of the inorganic electro-optic semiconductors ZnTe, GaP, and CdTe [4, 14]. However, a figure of merit for THz generation efficiency should be calculated from measured rather than calculated material parameters for a quantitative comparison [13]. Note that the electro-optic coefficient is not required for the calculation of the optimum crystal length in Section 4.

3. Optical properties

The optical group index ng,3 for light polarized along the polar axis was determined by measuring the time retardation of laser pulses transmitted through a 0.661 mm thick single crystal relative to air (for details see [17]). The laser pulses with a wavelength λ in the range from 600 to 2000 nm were provided by an optical parametric amplifier pumped by an amplified Ti:sapphire laser. In this spectral range, the refractive index dispersion n3(λ) can be described by a one-oscillator Sellmeier equation

n3(λ)=(n02+qλ02λ2λ02)1/2,
where ν0 = c/λ0 is the resonance frequency, q is the strength of the main oscillator, and n0 takes the off-resonant contributions of all other oscillators into account. The corresponding dispersion of the optical group index is given by
ng,3(λ)=n3(λ)λdn3dλ(λ).
The Sellmeier parameters listed in Table 1 were obtained by the best fit of the theoretical dispersion function to the measured group index data. These parameters are also accurate for the Sellmeier equation for the refractive index n3(λ), since ng,3(λ) was measured in a broad spectral range with a high dispersion [17]. The measured data and the fitted dispersion curves are plotted in Fig. 1(a).

Tables Icon

Table 1. Parameters of the Sellmeier dispersion formula for the refractive index n3(λ) of HMQ-TMS crystals in the spectral range between 600 and 2000 nm [see Eq. (1)].

 

Fig. 1 Linear optical properties of HMQ-TMS crystals for light polarized along the polar axis. (a) Optical group index ng,3 (dots). The dotted line represents the best fit to the measured data of the Sellmeier equation for the optical group index ng,3 according to the Eqs. (1) and (2) with the parameters listed in Table 1. The solid line corresponds to the refractive index n3 calculated from the Sellmeier equation. (b) Absorption coefficient α3. The inset shows a semilogarithmic plot of α3 for a better readability of the graph near the absorption edge.

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The transmission of light polarized along the polar axis of the crystal was measured in the same spectral range. The absorption coefficient α3 was calculated from the measured transmission data taking the Fresnel losses into account [see Fig. 1(b)]. The cutoff wavelength, which we define for an absorption coefficient of 10 cm−1, is 577 nm. The absorption coefficient is smaller than 1.5 cm−1 in the whole wavelength range between 800 and 1500 nm. In addition, we measured the two-photon absorption coefficient β3 = 2.5 ± 0.4 cm/GW at λ = 800 nm and β3 = 0.4 ± 0.1 cm/GW at λ = 1300 nm using the method described by Bechtel and Smith [18]. The obtained value at 800 nm is approximately half the value of OH1 (β3 = 4.5 ± 0.4 cm/GW), which we measured for comparison. At λ = 1300 nm, the two-photon absorption coefficient of HMQ-TMS is comparable to the one of OH1 (β3 = 0.3 cm/GW) and smaller than the one of DAST (β1 = 0.7 cm/GW) [8, 10].

The refractive index n3 and the absorption coefficient α3 were also measured at THz frequencies using THz time-domain spectroscopy. The refractive index drops from 2.3 to 2.2 as the THz frequency increases from 0.3 to 1.5 THz and matches the NIR group index well, in particular for wavelengths between 800 and 1000 nm [see Figs. 1(a) and 2(a)]. The absorption is low to moderate (α3 < 100 cm−1) in the range from 0.6 to 1.5 THz and below the detection limit of the measurement from 0.3 to 0.6 THz [see Fig. 2(b)]. Thus, the HMQ-TMS crystal has a considerably lower maximum THz absorption in the shown frequency range than the molecular salt crystals DAST (600 cm−1) and DSTMS (240 cm−1), which is necessary for the generation of a gap-free THz spectrum [8, 9, 19]. Altogether, the HMQ-TMS crystal is a promising candidate for highly efficient THz generation in this frequency range due to its high transparency in the NIR and THz ranges, good phase-matching properties, and high optical nonlinearity.

 

Fig. 2 (a) Refractive index n3 and (b) absorption coefficient α3 of HMQ-TMS crystals for THz waves polarized along the polar axis.

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4. Generation of THz pulses in HMQ-TMS crystals

The conversion efficiency of THz generation in a nonlinear optical crystal depends on the linear and nonlinear optical properties and thickness of the crystal and on laser parameters. For a theoretical calculation of the conversion efficiency, the nonlinear wave equation for the generated THz signal is typically solved in the frequency domain. An exact solution can be found if plane waves and a non-depleted pump wave are assumed and cascaded second order and higher order nonlinear optical effects are excluded [20]. If only forward traveling waves are considered, the spectral amplitude at the THz frequency ν is given by [8]

|ETHz(ν)|=|μ0χ(2)(ν,λ)2πνI(ν)no(λ)[c2πν(αT(ν)2+αo(λ))+i(nT(ν)+ng(λ))]|lgen(ν,λ,l),
where μ0 is the permeability of vacuum, c is the speed of light in vacuum, χ(2)(ν, λ) is the nonlinear optical susceptibility for optical rectification, I(ν) is the Fourier transform of the intensity profile of the laser pulse, nT (ν) and αT (ν) are the refractive index and the absorption coefficient at the THz frequency ν. no(λ), ng(λ) and αo(λ) are the refractive index, the group index and the absorption coefficient at the NIR wavelength λ. The dependence of the generated THz field amplitude on the crystal length l is described by the effective generation length
lgen(ν,λ,l)=(exp(2αo(λ)l)+exp(αT(ν)l)2exp([αo(λ)+αT(ν)2]l)cos(πllc(ν,λ))(αT(ν)2αo(λ))2+(πlc(ν,λ))2)1/2,
where
lc(ν,λ)=c2ν|nT(ν)ng(λ)|
is the coherence length for optical rectification. In addition, we define the optimum crystal length loptimum as the (smallest) crystal length which gives the maximum effective generation length, i.e., lgen(ν, λ, loptimum) = supl>0 lgen(ν, λ, l). The effective generation length lgen is equal to the crystal length l in the case of ideal phase-matching (nT = ng) and zero absorption (αo = αT = 0) and it is a bounded function of l if there is a phase-mismatch or absorption, in which case loptimum is finite. For a finite coherence length and zero absorption, lgen is given by the function
lgen(ν,λ,l)=|sinc(πl2lc(ν,λ))l|,
which has a maximum of 2lc at l = loptimum = lc. If there is both phase-mismatch and absorption, lgen has a lower maximum than 2lc at l = loptimum < lc. The nonlinear absorption of the pump beam at very high pump intensities, which leads to smaller optimum crystal lengths is not included in this simple model.

From the measured dispersion, we deduce that HMQ-TMS crystals have good type-0 phase-matching properties for THz pulse generation through optical rectification of laser pulses from any of the most important fiber or solid-state femtosecond laser systems operating at wavelengths between 800 and 1500 nm. The coherence length is larger than 0.5 mm for the generation of frequencies between 0.3 and 1.5 THz in this range of laser wavelengths. The phase-matching is nearly ideal for THz frequencies between 0.3 and 0.8 THz at the laser wavelength of 800 nm and between 0.8 and 1.5 THz at 1000 nm. Figure 3 shows the optimum crystal length loptimum for the highest conversion efficiency as a function of THz frequency and the maximum effective generation length lgen(ν, λ, loptimum) for the three laser wavelengths 800, 1000, and 1500 nm.

 

Fig. 3 (a) The optimum crystal length for the highest conversion efficiency and (b) the maximum effective generation length for THz pulse generation in HMQ-TMS crystals for the laser wavelengths 800 nm (black solid line), 1000 nm (red dotted line), and 1500 nm (blue dashed line).

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We generated THz pulses in a 0.2 mm thick HMQ-TMS crystal through optical rectification of 100 fs laser pulses at 1000 nm, which were frequency-doubled idler pulses from an optical parametric amplifier pumped by an amplified Ti:sapphire laser (see Fig. 4). The THz pulses were detected by electro-optic sampling in a 1 mm thick ZnTe crystal using a probe beam at 800 nm [2]. For comparison, THz pulses were generated in a 0.3 mm thick GaP crystal under identical conditions. The THz pulses emitted from the HMQ-TMS crystal showed a 41 times higher energy, a 5.4 times higher peak amplitude [see Fig. 4(a)], and a 7.1 times higher peak spectral amplitude [see Fig. 4(b)] than the ones emitted from the GaP crystal.

 

Fig. 4 THz pulse generated in a 0.2 mm thick HMQ-TMS crystal and detected in a 1 mm thick ZnTe crystal (red solid line). (a) Time-domain and (b) frequency-domain signal. THz pulse emitted from a 0.3 mm thick GaP crystal under identical conditions for comparison (black dotted line).

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We also generated THz pulses in a 0.661 mm thick HMQ-TMS crystal and in a 0.731 mm thick OH1 crystal using laser pulses with a central wavelength of λ = 1300 nm, a duration of 100 fs and a peak intensity of 100 GW/cm2. The energy conversion efficiency was ηHMQ-TMS = 4.9 × 10−4 for the HMQ-TMS crystal and ηOH1 = 3.6 × 10−3 for the OH1 crystal. The coherence length of both crystals is sufficiently large, they have comparable linear and nonlinear NIR absorption, and HMQ-TMS has a larger THz absorption than OH1. Thus, we can estimate the nonlinear optical susceptibility of HMQ-TMS from the ratio of the conversion efficiencies, χHMQ-TMS(2)/χOH1(2)ηHMQ-TMS/ηOH1=37%, where χOH1(2)=560pm/V [10].

5. Conclusions

We have measured the refractive index and absorption coefficient of the organic ionic crystal HMQ-TMS for light polarized along its polar axis in the optical wavelength range from 600 to 2000 nm and in the THz frequency range from 0.3 to 1.5 THz. The linear absorption is very low for wavelengths of femtosecond lasers and relatively low for THz waves. The HMQ-TMS crystal shows good phase-matching properties for THz generation, in particular for the generation of frequencies between 0.3 and 0.8 THz at the laser wavelength of 800 nm and between 0.8 and 1.5 THz at 1000 nm. We have shown that the HMQ-TMS crystal allows more efficient THz generation than the often used GaP crystal at the laser wavelength of 1000 nm.

Acknowledgments

This work was supported by the National Centre of Competence in Research Molecular Ultra-fast Science and Technology (NCCR MUST)—a research instrument of the Swiss National Science Foundation (SNSF), Mid-career Researcher Program ( NRF-2013R1A2A2A01007232), Priority Research Centers Program ( 2009-0093826) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, and the Ministry of Education.

References and links

1. M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007). [CrossRef]  

2. A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996). [CrossRef]  

3. G. Chang, C. J. Divin, C.-H. Liu, S. L. Williamson, A. Galvanauskas, and T. B. Norris, “Power scalable compact THz system based on an ultrafast Yb-doped fiber amplifier,” Opt. Express 14, 7909–7913 (2006). [CrossRef]   [PubMed]  

4. B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008). [CrossRef]  

5. F. Blanchard, L. Razzari, H. C. Bandulet, G. Sharma, R. Morandotti, J. C. Kieffer, T. Ozaki, M. Reid, H. F. Tiedje, H. K. Haugen, and F. A. Hegmann, “Generation of 1.5 μJ single-cycle terahertz pulses by optical rectification from a large aperture ZnTe crystal,” Opt. Express 15, 13212–13220 (2007). [CrossRef]   [PubMed]  

6. M. C. Hoffmann, K.-L. Yeh, J. Hebling, and K. A. Nelson, “Efficient terahertz generation by optical rectification at 1035 nm,” Opt. Express 15, 11706–11713 (2007). [CrossRef]   [PubMed]  

7. S.-W. Huang, E. Granados, W. R. Huang, K.-H. Hong, L. E. Zapata, and F. X. Kärtner, “High conversion efficiency, high energy terahertz pulses by optical rectification in cryogenically cooled lithium niobate,” Opt. Lett. 38, 796–798 (2013). [CrossRef]   [PubMed]  

8. A. Schneider, M. Neis, M. Stillhart, B. Ruiz, R. U. A. Khan, and P. Günter, “Generation of terahertz pulses through optical rectification in organic DAST crystals: theory and experiment,” J. Opt. Soc. Am. B 23, 1822– 1835 (2006). [CrossRef]  

9. M. Stillhart, A. Schneider, and P. Günter, “Optical properties of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate crystals at terahertz frequencies,” J. Opt. Soc. Am. B 25, 1914–1919 (2008). [CrossRef]  

10. F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008). [CrossRef]   [PubMed]  

11. C. P. Hauri, C. Ruchert, C. Vicario, and F. Ardana, “Strong-field single-cycle THz pulses generated in an organic crystal,” Appl. Phys. Lett. 99, 161116 (2011). [CrossRef]  

12. C. Ruchert, C. Vicario, and C. P. Hauri, “Scaling submillimeter single-cycle transients toward megavolts per centimeter field strength via optical rectification in the organic crystal OH1,” Opt. Lett. 37, 899–901 (2012). [CrossRef]   [PubMed]  

13. F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009). [CrossRef]  

14. J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013). [CrossRef]   [PubMed]  

15. B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014). [CrossRef]  

16. P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011). [CrossRef]  

17. A. Schneider, F. D. J. Brunner, and P. Günter, “Determination of the refractive index over a wide wavelength range through time-delay measurements of femtosecond pulses,” Opt. Commun. 275, 354–358 (2007). [CrossRef]  

18. J. H. Bechtel and W. L. Smith, “Two-photon absorption in semiconductors with picosecond laser pulses,” Phys. Rev. B 13, 3515–3522 (1976). [CrossRef]  

19. P. D. Cunningham and L. M. Hayden, “Optical properties of DAST in the THz range,” Opt. Express 18, 23620–23625 (2010). [CrossRef]   [PubMed]  

20. A. Schneider, “Theory of terahertz pulse generation through optical rectification in a nonlinear optical material with a finite size,” Phys. Rev. A 82, 033825 (2010). [CrossRef]  

References

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  1. M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
    [Crossref]
  2. A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996).
    [Crossref]
  3. G. Chang, C. J. Divin, C.-H. Liu, S. L. Williamson, A. Galvanauskas, and T. B. Norris, “Power scalable compact THz system based on an ultrafast Yb-doped fiber amplifier,” Opt. Express 14, 7909–7913 (2006).
    [Crossref] [PubMed]
  4. B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
    [Crossref]
  5. F. Blanchard, L. Razzari, H. C. Bandulet, G. Sharma, R. Morandotti, J. C. Kieffer, T. Ozaki, M. Reid, H. F. Tiedje, H. K. Haugen, and F. A. Hegmann, “Generation of 1.5 μJ single-cycle terahertz pulses by optical rectification from a large aperture ZnTe crystal,” Opt. Express 15, 13212–13220 (2007).
    [Crossref] [PubMed]
  6. M. C. Hoffmann, K.-L. Yeh, J. Hebling, and K. A. Nelson, “Efficient terahertz generation by optical rectification at 1035 nm,” Opt. Express 15, 11706–11713 (2007).
    [Crossref] [PubMed]
  7. S.-W. Huang, E. Granados, W. R. Huang, K.-H. Hong, L. E. Zapata, and F. X. Kärtner, “High conversion efficiency, high energy terahertz pulses by optical rectification in cryogenically cooled lithium niobate,” Opt. Lett. 38, 796–798 (2013).
    [Crossref] [PubMed]
  8. A. Schneider, M. Neis, M. Stillhart, B. Ruiz, R. U. A. Khan, and P. Günter, “Generation of terahertz pulses through optical rectification in organic DAST crystals: theory and experiment,” J. Opt. Soc. Am. B 23, 1822– 1835 (2006).
    [Crossref]
  9. M. Stillhart, A. Schneider, and P. Günter, “Optical properties of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate crystals at terahertz frequencies,” J. Opt. Soc. Am. B 25, 1914–1919 (2008).
    [Crossref]
  10. F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
    [Crossref] [PubMed]
  11. C. P. Hauri, C. Ruchert, C. Vicario, and F. Ardana, “Strong-field single-cycle THz pulses generated in an organic crystal,” Appl. Phys. Lett. 99, 161116 (2011).
    [Crossref]
  12. C. Ruchert, C. Vicario, and C. P. Hauri, “Scaling submillimeter single-cycle transients toward megavolts per centimeter field strength via optical rectification in the organic crystal OH1,” Opt. Lett. 37, 899–901 (2012).
    [Crossref] [PubMed]
  13. F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009).
    [Crossref]
  14. J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
    [Crossref] [PubMed]
  15. B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
    [Crossref]
  16. P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
    [Crossref]
  17. A. Schneider, F. D. J. Brunner, and P. Günter, “Determination of the refractive index over a wide wavelength range through time-delay measurements of femtosecond pulses,” Opt. Commun. 275, 354–358 (2007).
    [Crossref]
  18. J. H. Bechtel and W. L. Smith, “Two-photon absorption in semiconductors with picosecond laser pulses,” Phys. Rev. B 13, 3515–3522 (1976).
    [Crossref]
  19. P. D. Cunningham and L. M. Hayden, “Optical properties of DAST in the THz range,” Opt. Express 18, 23620–23625 (2010).
    [Crossref] [PubMed]
  20. A. Schneider, “Theory of terahertz pulse generation through optical rectification in a nonlinear optical material with a finite size,” Phys. Rev. A 82, 033825 (2010).
    [Crossref]

2014 (1)

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

2013 (2)

S.-W. Huang, E. Granados, W. R. Huang, K.-H. Hong, L. E. Zapata, and F. X. Kärtner, “High conversion efficiency, high energy terahertz pulses by optical rectification in cryogenically cooled lithium niobate,” Opt. Lett. 38, 796–798 (2013).
[Crossref] [PubMed]

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

2012 (1)

2011 (2)

C. P. Hauri, C. Ruchert, C. Vicario, and F. Ardana, “Strong-field single-cycle THz pulses generated in an organic crystal,” Appl. Phys. Lett. 99, 161116 (2011).
[Crossref]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

2010 (2)

P. D. Cunningham and L. M. Hayden, “Optical properties of DAST in the THz range,” Opt. Express 18, 23620–23625 (2010).
[Crossref] [PubMed]

A. Schneider, “Theory of terahertz pulse generation through optical rectification in a nonlinear optical material with a finite size,” Phys. Rev. A 82, 033825 (2010).
[Crossref]

2009 (1)

F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009).
[Crossref]

2008 (3)

2007 (4)

2006 (2)

1996 (1)

A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996).
[Crossref]

1976 (1)

J. H. Bechtel and W. L. Smith, “Two-photon absorption in semiconductors with picosecond laser pulses,” Phys. Rev. B 13, 3515–3522 (1976).
[Crossref]

Ardana, F.

C. P. Hauri, C. Ruchert, C. Vicario, and F. Ardana, “Strong-field single-cycle THz pulses generated in an organic crystal,” Appl. Phys. Lett. 99, 161116 (2011).
[Crossref]

Baek, I. H.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

Baek, I.-H.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Bandulet, H. C.

Bechtel, J. H.

J. H. Bechtel and W. L. Smith, “Two-photon absorption in semiconductors with picosecond laser pulses,” Phys. Rev. B 13, 3515–3522 (1976).
[Crossref]

Blanchard, F.

Brunner, F. D. J.

F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009).
[Crossref]

F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
[Crossref] [PubMed]

A. Schneider, F. D. J. Brunner, and P. Günter, “Determination of the refractive index over a wide wavelength range through time-delay measurements of femtosecond pulses,” Opt. Commun. 275, 354–358 (2007).
[Crossref]

Chang, G.

Cunningham, P. D.

Divin, C. J.

Galvanauskas, A.

Granados, E.

Günter, P.

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009).
[Crossref]

M. Stillhart, A. Schneider, and P. Günter, “Optical properties of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate crystals at terahertz frequencies,” J. Opt. Soc. Am. B 25, 1914–1919 (2008).
[Crossref]

F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
[Crossref] [PubMed]

A. Schneider, F. D. J. Brunner, and P. Günter, “Determination of the refractive index over a wide wavelength range through time-delay measurements of femtosecond pulses,” Opt. Commun. 275, 354–358 (2007).
[Crossref]

A. Schneider, M. Neis, M. Stillhart, B. Ruiz, R. U. A. Khan, and P. Günter, “Generation of terahertz pulses through optical rectification in organic DAST crystals: theory and experiment,” J. Opt. Soc. Am. B 23, 1822– 1835 (2006).
[Crossref]

Haugen, H. K.

Hauri, C. P.

Hayden, L. M.

Hebling, J.

Hegmann, F. A.

Heinz, T. F.

A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996).
[Crossref]

Hoffmann, M. C.

Hong, K.-H.

Huang, S.-W.

Huang, W. R.

Jazbinšek, M.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
[Crossref] [PubMed]

Jeong, J.-H.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Kang, B. J.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

Kang, B.-J.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Kärtner, F. X.

Khan, R. U. A.

Kieffer, J. C.

Kim, J.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Kim, J.-H.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Kim, J.-S.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Kim, J.-T.

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Kim, P.-J.

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Kwon, O.-P.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Kwon, O-P.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
[Crossref] [PubMed]

Kwon, S.-J.

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
[Crossref] [PubMed]

Lee, J.-H.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Lee, S.-C.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Lee, S.-H.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

Lee, Y. S.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Liu, C.-H.

Matthäus, G.

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Morandotti, R.

Nahata, A.

A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996).
[Crossref]

Neis, M.

Nelson, K. A.

Nolte, S.

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Norris, T. B.

Notni, G.

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Ozaki, T.

Pradarutti, B.

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Razzari, L.

Reid, M.

Riehemann, S.

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Rotermund, F.

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Ruchert, C.

Ruiz, B.

Schneider, A.

A. Schneider, “Theory of terahertz pulse generation through optical rectification in a nonlinear optical material with a finite size,” Phys. Rev. A 82, 033825 (2010).
[Crossref]

F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009).
[Crossref]

F. D. J. Brunner, O-P. Kwon, S.-J. Kwon, M. Jazbinšek, A. Schneider, and P. Günter, “A hydrogen-bonded organic nonlinear optical crystal for high-efficiency terahertz generation and detection,” Opt. Express 16, 16496–16508 (2008).
[Crossref] [PubMed]

M. Stillhart, A. Schneider, and P. Günter, “Optical properties of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate crystals at terahertz frequencies,” J. Opt. Soc. Am. B 25, 1914–1919 (2008).
[Crossref]

A. Schneider, F. D. J. Brunner, and P. Günter, “Determination of the refractive index over a wide wavelength range through time-delay measurements of femtosecond pulses,” Opt. Commun. 275, 354–358 (2007).
[Crossref]

A. Schneider, M. Neis, M. Stillhart, B. Ruiz, R. U. A. Khan, and P. Günter, “Generation of terahertz pulses through optical rectification in organic DAST crystals: theory and experiment,” J. Opt. Soc. Am. B 23, 1822– 1835 (2006).
[Crossref]

Sharma, G.

Smith, W. L.

J. H. Bechtel and W. L. Smith, “Two-photon absorption in semiconductors with picosecond laser pulses,” Phys. Rev. B 13, 3515–3522 (1976).
[Crossref]

Stillhart, M.

Tiedje, H. F.

Tonouchi, M.

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
[Crossref]

Tünnermann, A.

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Vicario, C.

Weling, A. S.

A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996).
[Crossref]

Williamson, S. L.

Yeh, K.-L.

Yun, H.

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Zapata, L. E.

Appl. Phys. Lett. (3)

A. Nahata, A. S. Weling, and T. F. Heinz, “A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling,” Appl. Phys. Lett. 69, 2321–2323 (1996).
[Crossref]

C. P. Hauri, C. Ruchert, C. Vicario, and F. Ardana, “Strong-field single-cycle THz pulses generated in an organic crystal,” Appl. Phys. Lett. 99, 161116 (2011).
[Crossref]

F. D. J. Brunner, A. Schneider, and P. Günter, “Velocity-matched terahertz generation by optical rectification in an organic nonlinear optical crystal using a Ti:sapphire laser,” Appl. Phys. Lett. 94, 061119 (2009).
[Crossref]

CrystEngComm (1)

P.-J. Kim, J.-H. Jeong, M. Jazbinšek, S.-J. Kwon, H. Yun, J.-T. Kim, Y. S. Lee, I.-H. Baek, F. Rotermund, P. Günter, and O-P. Kwon, “Acentric nonlinear optical N-benzyl stilbazolium crystals with high environmental stability and enhanced molecular nonlinearity in solid state,” CrystEngComm 13, 444–451 (2011).
[Crossref]

Curr. Appl. Phys. (1)

B. J. Kang, I. H. Baek, J.-H. Jeong, J.-S. Kim, S.-H. Lee, O-P. Kwon, and F. Rotermund, “Characteristics of efficient few-cycle terahertz radiation generated in as-grown nonlinear organic single crystals,” Curr. Appl. Phys. 14, 403–406 (2014).
[Crossref]

J. Opt. Soc. Am. B (2)

Nat. Photonics (1)

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
[Crossref]

Opt. Commun. (2)

A. Schneider, F. D. J. Brunner, and P. Günter, “Determination of the refractive index over a wide wavelength range through time-delay measurements of femtosecond pulses,” Opt. Commun. 275, 354–358 (2007).
[Crossref]

B. Pradarutti, G. Matthäus, S. Riehemann, G. Notni, S. Nolte, and A. Tünnermann, “Highly efficient terahertz electro-optic sampling by material optimization at 1060 nm,” Opt. Commun. 281, 5031–5035 (2008).
[Crossref]

Opt. Express (5)

Opt. Lett. (2)

Phys. Rev. A (1)

A. Schneider, “Theory of terahertz pulse generation through optical rectification in a nonlinear optical material with a finite size,” Phys. Rev. A 82, 033825 (2010).
[Crossref]

Phys. Rev. B (1)

J. H. Bechtel and W. L. Smith, “Two-photon absorption in semiconductors with picosecond laser pulses,” Phys. Rev. B 13, 3515–3522 (1976).
[Crossref]

Sci. Rep. (1)

J.-H. Jeong, B.-J. Kang, J.-S. Kim, M. Jazbinšek, S.-H. Lee, S.-C. Lee, I.-H. Baek, H. Yun, J. Kim, Y. S. Lee, J.-H. Lee, J.-H. Kim, F. Rotermund, and O.-P. Kwon, “High-power broadband organic THz generator,” Sci. Rep. 3, 3200 (2013).
[Crossref] [PubMed]

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Figures (4)

Fig. 1
Fig. 1 Linear optical properties of HMQ-TMS crystals for light polarized along the polar axis. (a) Optical group index ng,3 (dots). The dotted line represents the best fit to the measured data of the Sellmeier equation for the optical group index ng,3 according to the Eqs. (1) and (2) with the parameters listed in Table 1. The solid line corresponds to the refractive index n3 calculated from the Sellmeier equation. (b) Absorption coefficient α3. The inset shows a semilogarithmic plot of α3 for a better readability of the graph near the absorption edge.
Fig. 2
Fig. 2 (a) Refractive index n3 and (b) absorption coefficient α3 of HMQ-TMS crystals for THz waves polarized along the polar axis.
Fig. 3
Fig. 3 (a) The optimum crystal length for the highest conversion efficiency and (b) the maximum effective generation length for THz pulse generation in HMQ-TMS crystals for the laser wavelengths 800 nm (black solid line), 1000 nm (red dotted line), and 1500 nm (blue dashed line).
Fig. 4
Fig. 4 THz pulse generated in a 0.2 mm thick HMQ-TMS crystal and detected in a 1 mm thick ZnTe crystal (red solid line). (a) Time-domain and (b) frequency-domain signal. THz pulse emitted from a 0.3 mm thick GaP crystal under identical conditions for comparison (black dotted line).

Tables (1)

Tables Icon

Table 1 Parameters of the Sellmeier dispersion formula for the refractive index n3(λ) of HMQ-TMS crystals in the spectral range between 600 and 2000 nm [see Eq. (1)].

Equations (6)

Equations on this page are rendered with MathJax. Learn more.

n 3 ( λ ) = ( n 0 2 + q λ 0 2 λ 2 λ 0 2 ) 1 / 2 ,
n g , 3 ( λ ) = n 3 ( λ ) λ d n 3 d λ ( λ ) .
| E THz ( ν ) | = | μ 0 χ ( 2 ) ( ν , λ ) 2 π ν I ( ν ) n o ( λ ) [ c 2 π ν ( α T ( ν ) 2 + α o ( λ ) ) + i ( n T ( ν ) + n g ( λ ) ) ] | l gen ( ν , λ , l ) ,
l gen ( ν , λ , l ) = ( exp ( 2 α o ( λ ) l ) + exp ( α T ( ν ) l ) 2 exp ( [ α o ( λ ) + α T ( ν ) 2 ] l ) cos ( π l l c ( ν , λ ) ) ( α T ( ν ) 2 α o ( λ ) ) 2 + ( π l c ( ν , λ ) ) 2 ) 1 / 2 ,
l c ( ν , λ ) = c 2 ν | n T ( ν ) n g ( λ ) |
l gen ( ν , λ , l ) = | sinc ( π l 2 l c ( ν , λ ) ) l | ,

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