Second-harmonic generation in resonant waveguide gratings incorporating ionic self-assembled monolayer polymer films
ABSTRACT Experimental results on resonantly excited second-harmonic generation (SHG) in a periodic ionically self-assembled monolayer (ISAM) film are reported. A double-layer guided-mode resonance filter (GMRF) structure is coated with 40 bilayers of pyrlium-based chi(2) ISAM thin film and excited with the fundamental of a Nd:YAG laser. Enhanced second-harmonic conversion in the ISAM film is achieved because of the local field enhancement associated with the fundamental resonating leaky mode. This method of SHG is particularly promising, as the ISAM films under investigation exhibit anomalous dispersion that may be applied for phase matching to improve nonlinear conversion efficiency.
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ABSTRACT: Guided mode resonance (GMR) enhanced second- and third-harmonic generation (SHG and THG) is demonstrated in an azo-polymer resonant waveguide grating (RWG), comprised of a poled azo-polymer layer on top of a textured SU8 substrate with a thin intervening layer of TiO<sub>2</sub>. Strong SHG and THG outputs are observed by matching either in-coming fundamental- or out-going harmonic-wavelength to the GMR wavelengths of the azo-polymer RWG. Without the azo-polymer coating, pure TiO<sub>2</sub> RWGs, do not generate any detectable SHG using a fundamental beam peak intensity of 2 MW/cm<sup>2</sup>. Without the textured TiO<sub>2</sub> layer, a planar poled azo-polymer layer results in 3650 times less SHG than the full nonlinear RWG structure under identical excitation conditions. Rigorous coupled-wave analysis calculations confirm that this enhancement of the nonlinear conversion is due to strong local electric fields that are generated at the interfaces of the TiO<sub>2</sub> and azo-polymer layers when the RWG is excited at resonant wavelengths associated with both SHG and THG conversion processes.Optics Express 02/2014; 22(3):2790-7. DOI:10.1364/OE.22.002790 · 3.53 Impact Factor
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ABSTRACT: Pyrylium fluoroborates undergo a wide range of synthetically useful reactions because of the positive charge. And the electron accepting nature has resulted in their widespread use as sensitizers for photo-induced electron transfer (PET) reactions. In this experiment, 2,6-disubstituted pyrylium fluoroborates are synthesized from the reaction between -chloroacetophenone and excess orthoformate in an acidic medium (acetic anhydride/acid). Synthesized products are confirmed by , FT-IR and TOF Mass spectroscopies. Also, photo-properties are analyzed with an UV-Vis spectrophotometer.Journal of the Korean Industrial and Engineering Chemistry 01/2009; 20(3).
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ABSTRACT: Due to its high conductivity, pyrylium has been frequently used in electron transfer reactions or in the synthesis of various organic materials. It has also been used as a sensor material. Traditionally, the compounds have been synthesized using various methods; mostly in a multiple steps. In this study, two pyrylium salts, 2, 6-di-(4'-methylphenyl) pyrylium fluoroborate and perchlorate were synthesized. The synthesis of these products was confirmed by 1H-NMR, LC/TOF-MS and FT-IR analyses while their photo-properties were analyzed using UV/VIS spectrophotometry. In addition, the electron transfer capacities of the salts were analyzed with a conductivity meter, it was found that their electron conductivities were high. When the synthesized compounds were dissolved in acetone, a green fluorescent material was observed to form. The fluorescent material can be used as a sensitizer in the electrical industry.01/2012; 21(1). DOI:10.5369/JSST.2012.21.1.013