Abstract-Generation of high-field terahertz pulses in an HMQ-TMS organic crystal pumped by an ytterbium laser at 1030 nm

Andrea Rovere, Young-Gyun Jeong, Riccardo Piccoli, Seung-Heon Lee, Seung-Chul Lee, O-Pil Kwon, Mojca Jazbinsek, Roberto Morandotti, and Luca Razzari

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-3-2509

We present the generation of high-peak-electric-field terahertz pulses via collinear optical rectification in a 2-(4-hydroxy-3-methoxystyryl)-1-methilquinolinium-2,4,6-trimethylbenzenesulfonate (HMQ-TMS) organic crystal. The crystal is pumped by an amplified ytterbium laser system, emitting 170-fs-long pulses centered at 1030 nm. A terahertz peak electric field greater than 200 kV/cm is obtained for 420 µJ of optical pump energy, with an energy conversion efficiency of 0.26% - about two orders of magnitude higher than in common inorganic crystals collinearly pumped by amplified femtosecond lasers. An open-aperture Z-scan measurement performed on an n-doped InGaAs thin film using such terahertz source shows a nonlinear increase in the terahertz transmission of about 2.2 times. Our findings demonstrate the potential of this terahertz generation scheme, based on ytterbium laser technology, as a simple and efficient alternative to the existing intense table-top terahertz sources. In particular, we show that it can be readily used to explore nonlinear effects at terahertz frequencies.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Tunable multi-cycle THz generation in organic crystal HMQ-TMS

Jian Lu,1 Harold Y. Hwang,1 Xian Li,1 Seung-Heon Lee,2 O-Pil Kwon2 and Keith A. Nelson1,*

 1 Deartment of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 2 Department of Molecular Science and Technology, Ajou University, Suwon 443-749, South Korea * kanelson@mit.edu

 https://www.osapublishing.org/view_article.cfm?gotourl=https%3A%2F%2Fwww%2Eosapublishing%2Eorg%2FDirectPDFAccess%2F0129DC5F-F642-F10F-6A6F73D0AFC3655B_324474%2Foe-23-17-22723%2Epdf%3Fda%3D1%26id%3D324474%26seq%3D0%26mobile%3Dno&org=

Abstract: We report on the generation of continuously tunable multi-cycle THz pulses with center frequencies from 0.3 to 0.8 THz in the organic nonlinear crystal, HMQ-TMS [2-(4-hydroxy-3-methoxystyryl)-1- methylquinolinium 2,-4,-6-trimethylbenzenesulfonate], by collinearly phase matched optical rectification of temporally shaped 800 nm pulses. The generation of harmonic frequency components inherent in the pulse shaper is selectively suppressed by varying the generation crystal thickness. THz pulses generated from HMQ-TMS show up to 20 times higher pulse energies compared to the benchmark inorganic THz generator ZnTe under identical conditions. The THz energy conversion efficiencies are measured to be on the order of 10−5 .

©2015 Optical Society of America OCIS codes: (160.4890) Organic materials; (190.0190) Nonlinear optics; (300.6495) Spectroscopy, terahertz. 

Abstract-THz generation by optical rectification of near-infrared laser pulses in the organic nonlinear optical crystal HMQ-TMS

Fabian D. J. Brunner, Seung-Heon Lee, O-Pil Kwon, and Thomas Feurer  »View Author Affiliations

Optical Materials Express, Vol. 4, Issue 8, pp. 1586-1592 (2014)
http://dx.doi.org/10.1364/OME.4.001586

http://www.opticsinfobase.org/ome/abstract.cfm?uri=ome-4-8-1586

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 (l_c > 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

Abstract-Generation of broadband THz pulses in organic crystal OH1 at room temperature and 10 K

Andrei G. Stepanov, Clemens Ruchert, Julien Levallois, Christian Erny, and Christoph P. Hauri  »View Author Affiliations http://www.opticsinfobase.org/ome/abstract.cfm?uri=ome-4-4-870

Optical Materials Express, Vol. 4, Issue 4, pp. 870-875 (2014)
http://dx.doi.org/10.1364/OME.4.000870

We studied the effects of cryogenic cooling of a 2-[3-(4-hydroxystyryl)-5, 5-dimethylcyclohex-2-enylidene] malononitrile (OH1) crystal on the generation of broadband THz pulses via collinear optical rectification of 1350 nm femtosecond laser pulses. Cooling of the OH1 crystal from room temperature to 10 K leads to a ~10% increase of the pump-to-THz energy conversion efficiency and a shift of the THz pulse spectra to a higher frequency range. Both effects are due the temperature variation of THz absorption and the refractive index of the OH1 crystal. This conclusion has been verified by temperature dependent measurements of the linear absorption in the THz frequency region. An approach to obtain a stronger increase of the THz generation efficiency at cryogenic cooling of the OH1 crystal is discussed.

© 2014 Optical Society of America