Zürich, Switzerland
Zürich, Switzerland

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Majkic A.,Jozef Stefan Institute | Majkic A.,University of Ljubljana | Zgonik M.,Jozef Stefan Institute | Zgonik M.,University of Ljubljana | And 5 more authors.
Applied Physics Letters | Year: 2014

We present a compact, room temperature, and narrowband terahertz source, based on difference-frequency generation in the organic nonlinear optical crystals OH1 (2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile). The system employs a specific dual-wavelength infrared laser that emits coaxial, synchronous 10-ns pulses of similar energy and duration at wavelengths of 1064 nm and 1030 nm by using Nd:YAG and Yb:YAG crystals within the split laser cavity. The common part of the laser cavity comprises an acousto-optic Q-switch and an output coupler. The output is frequency-mixed in a stack of several OH1 crystals in a quasi-phase-matching configuration, which is determined on the basis of refractive index and absorption measurements in the 1-11 THz range. The system generates terahertz radiation in pulse trains with 1.0μ W average power and a near-Gaussian intensity profile. © 2014 AIP Publishing LLC.

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2011.9.2 | Award Amount: 1.28M | Year: 2012

We propose an integrated high power single frequency terahertz source. This source will include a double wavelength solid-state infrared laser developed specifically for this application with two different intra-cavity laser materials that will emit at close but distinct infrared wavelengths.\nThe combination of the two emitted wavelengths in organic materials OH1 (2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile) and DSTMS (4-N,N-dimethylamino-4-N-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate) will produce high power monochromatic THz radiation at a frequency determined by the difference of the infrared wavelengths. We propose the realization of two different terahertz sources one operating at 4.27 THz, the other one at 9.31 THz. For these two THz sources we will develop two different double-frequency lasers TWIN-1 and TWIN-2. The first one will be based on Nd:YAG and Nd:YLF as laser hosts, with emission wavelengths at 1.33 m and 1.31 m. TWIN-2 uses Nd:YAG and Yb:YAG as laser hosts, with emission wavelengths at 1.03 m and 1.06 m. Both TWIN-1 and TWIN-2 will operate within a common and compact laser cavity.\nThe high THz power which can be generated in a compact device is due to the very high nonlinear optical susceptibility, the low THz absorption and the relatively high optical damage threshold and phase matchability of the OH1 and DSTMS crystals. A fully integrated, compact, all solid state system operating at room temperature will result from this research. This high power single terahertz frequency source will be used to investigate non-destructively high molecular weight polyethylene materials for biomedical applications.

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2009.3.8 | Award Amount: 3.52M | Year: 2010

In the SOFI project, new active optical waveguides and integrated optoelectronic circuits based on a novel silicon-organic hybrid technology are introduced. The technology is based on the low-cost CMOS process technology for fabrication of the optical waveguides - allowing for the convergence of electronics with optics. It is complemented by an organic layer that brings in new functionalities so far not available in silicon. Recent experiments have shown that such a technology can boost the signal processing in silicon far beyond 100 Gbit/s - which corresponds to a tripling of the state-of-the art bitrate.\nSOFI focuses on a proof-of concept implementation of ultra-fast ultra-low energy optical phase modulator waveguides such as needed in optical communications. These devices will ultimately be used to demonstrate an integrated circuit enabling the aggregation of low-bitrate electrical signals into a 100 Gbit/s OFDM data-stream having an energy consumption of only 5 fJ/bit. However, the SOFI technology is even more fundamental. By varying the characteristics of the organic layer one may also envision new sensing applications for environment and medicine.\nThe suggested approach is practical and disruptive. It combines the silicon CMOS technology and its standardized processes with the manifold possibilities offered by novel organic materials. This way, for instance, the processing speed limitations inherent in silicon are overcome, and an order-of-magnitude improvement can be achieved. More importantly, the new technology provides the lowest power consumption so far demonstrated for devices in its class. This is supported by calculations and first initial tests. The low power consumption is attributed to the tiny dimensions of the devices and to the fact, that optical switching is performed in the highly nonlinear cladding organic material rather than in silicon.

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2007.3.5 | Award Amount: 4.78M | Year: 2008

Components for multi spectral, real-time, room-temperature operating imaging and spectroscopy for multiple application fields as security technology, transport, production technology, or health and life-science are proposed. The first objective of the project is the development of a multi spectral imaging sensor working in the visible, long wave infrared, and terahertz band of the electromagnetic spectrum. All the imaging functionalities will be monolithically integrated on a CMOS chip and work at room-temperature. The second objective is to design a narrow band room-temperature large tuning range terahertz source and a high power fixed frequency source at 1 THz. The sources will be designed using laboratory equipment to achieve a proof of principle setup. The third objective is to combine the imaging sensor and the terahertz sources to a multispectral imaging and a spectroscopy subsystem. This two subsystems will allow doing visible, infrared, and active terahertz imaging, and terahertz spectroscopy. The spectroscopic functionality is achieved by sweeping the terahertz source over a large frequency range and subsequent acquisition with the terahertz sensor part.\nExperts from different possible application fields as security, transport, production technology, and life science and health will\ngive their contribution on defining the system- and components requirements at the beginning of the project and evaluate the\nperformance in the end. As a pilot application, the imaging and spectroscopy subsystems will be validated in an airport security environment.

Vicario C.,Paul Scherrer Institute | Jazbinsek M.,Rainbow Photonics AG | Ovchinnikov A.V.,RAS Joint Institute for High Temperatures | Chefonov O.V.,RAS Joint Institute for High Temperatures | And 4 more authors.
Optics Express | Year: 2015

We investigated Terahertz generation in organic crystals DSTMS, DAST and OH1 directly pumped by a Cr:forsterite laser at central wavelength of 1.25 μm. This pump laser technology provides a laser-to-THz energy conversion efficiency higher than 3 percent. Phase-matching is demonstrated over a broad 0.1-8 THz frequency range. In our simple setup we achieved hundred μJ pulses in tight focus resulting in electric and magnetic field larger than 10 MV/cm and 3 Tesla. ©2015 Optical Society of America.

Kim P.-J.,Ajou University | Jazbinsek M.,Rainbow Photonics AG | Kwon O.-P.,Ajou University
Crystal Growth and Design | Year: 2011

We report on selective growth of highly efficient nonlinear optical stilbazolium crystals by using sequential crystal growth in different solvent systems. Stilbazolium-salt crystals DSTMS (N,N-dimethylamino-N′- methylstilbazolium 2,4,6-trimethylbenzenesulfonate) with state-of-the-art nonlinear optical properties exhibit a thin plate-like morphology when grown in methanol and a thick trapezoidal-like morphology when grown in acetonitrile. We demonstrate morphology and thickness control of bulk DSTMS crystals by using sequential crystal growth by choosing a different solvent for growing bulk crystals as for growing seed crystals. For crystals growing in methanol solution from trapezoidal-like seed crystals grown in acetonitrile solution, the average growth rate is similar as in methanol alone, but the specific growth rate is considerably different: the aspect ratio of such crystals may be 1 order of magnitude larger than for crystals growing in methanol alone. For crystals growing in acetonitrile solution from thin plate-like seed crystals grown in methanol solution, the thickness slowly increases, while the lateral size remains similar. Such morphology and thickness control of DSTMS by sequential crystal growth in different solvents is a promising technique for practical applications, where crystals of a certain thickness are desired, for example, for THz-wave generation, frequency conversion, electro-optics, and field detection. © 2011 American Chemical Society.

Kim J.-S.,Ajou University | Jeong J.-H.,Ajou University | Yun H.,Ajou University | Jazbinsek M.,Rainbow Photonics AG | And 3 more authors.
Crystal Growth and Design | Year: 2013

We report on new acentric styryl quinolinium crystals with phenolic sulfonate counteranions and investigate their supramolecular interactions that affect their quadratic nonlinear optical properties. The phenolic group acting as an electron-donor as well as hydrogen-bond donor site is located at one end of the anion, while the sulfonate group acting as an electron-acceptor as well as hydrogen-bond acceptor site is located at the opposite end of the anion. New styryl quinolinium crystals with 4-hydroxybenzenesulfonate and 6-hydroxynaphthalene-2-sulfonate counteranions exhibit a large macroscopic optical nonlinearity with very efficient second harmonic generation (SHG) efficiency. In styryl quinolinium 4-hydroxybenzenesulfonate crystals, the styryl quinolinium cation chromophores exhibit an acentric ordering with a high order parameter close to 1.0, which is optimal for electro-optic applications or THz-wave generation. The 4-hydroxybenzenesulfonate counteranions form strong head-to-tail hydrogen bonds, and they are also packed in acentric layers. The direction of the polar axes in cation and anion layers is practically identical. Therefore, the introducing phenolic group acting as an electron-donor as well as hydrogen-bond donor to the sulfonate counteranion is a potential technique for crystal engineering to tailor molecular ordering as well as the physical properties of salt-type quinolinium derivatives. © 2013 American Chemical Society.

Choi E.-Y.,Ajou University | Jazbinsek M.,Rainbow Photonics AG | Kwon O.-P.,Ajou University
Crystal Growth and Design | Year: 2012

We report on the possibility to control the spontaneous nucleation of the highly efficient electro-optic phenolic polyene OH1 [2-(3-(4-hydroxystyryl)-5,5- dimethylcyclohex-2-enylidene)malononitrile] crystals by a liquid-type additive. Phosphoric acid is chosen as the additive because it is a liquid and much more polar than the growth solvent, methanol. The width of the metastable zone of the OH1 crystals is significantly decreased in the presence of this additive, and fast spontaneous nucleation is observed. In the presence of phosphoric acid, the growth of bulk crystals with a size of 6 × 6 × 2 mm 3 and thin plate-like crystals with a large area of about 15 × 15 mm 2 is demonstrated. © 2011 American Chemical Society.

Choi E.-Y.,Ajou University | Choi E.-Y.,Korea Advanced Institute of Science and Technology | Jazbinsek M.,Rainbow Photonics AG | Jeong J.-H.,Ajou University | Kwon O.-P.,Ajou University
CrystEngComm | Year: 2012

We demonstrate a simultaneous crystal growth and purification method by using ionic additives for organic π-conjugated single crystals grown from impure materials, synthesized by the favorable Knoevenagel condensation reactions. The phenolic polyene OH1 (2-(3-(4-hydroxystyryl)-5,5- dimethylcyclohex-2-enylidene)malononitrile) single crystals grown in the presence of ionic organic additives, stilbazolium and pyridinium derivatives, exhibit a higher purity and better optical quality compared to crystals grown in the absence of the additives. © 2012 The Royal Society of Chemistry.

Monoszlai B.,Paul Scherrer Institute | Vicario C.,Paul Scherrer Institute | Jazbinsek M.,Rainbow Photonics AG | Hauri C.P.,Paul Scherrer Institute | Hauri C.P.,Ecole Polytechnique Federale de Lausanne
Optics Letters | Year: 2013

High-energy terahertz pulses are produced by optical rectification (OR) in organic crystals 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) and 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) by a Ti:sapphire amplifier system with 0.8 μm central wavelength. The simple scheme provides broadband spectra between 1 and 5 THz, when pumped by a collimated 60 fs near-IR pump pulse, and it is scalable in energy. Fluence-dependent conversion efficiency and damage threshold are reported, as well as optimized OR at visible wavelengths. © 2013 Optical Society of America.

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