Nonlinear optical properties of organic and polymeric materials
29 Sep 1983-
About: The article was published on 1983-09-29 and is currently open access. It has received 762 citations till now.
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Dissertation•
29 Jul 2004
TL;DR: In this article, the effect of forced convection, varying deposition time and varying dye concentration on the properties of PAH/Procion Brown films fabricated via the hybrid reactive deposition scheme was investigated.
Abstract: With a growing demand in industry for cost effective, increased data handling capabilities great attention has been paid to the study of various polymer systems for use in optical telecommunications. Inorganic crystals, currently used in such systems, have high performance, but are more expensive and less obtainable than organic materials. Recent advances in techniques for developing highly efficient and inexpensive organic polymeric electro-optic (EO) devices compatible with current state-of-the-art electronics have created an interest in the commercialization of such electro-optic devices. In light of the many advantages of utilizing organic materials for electro-optic applications, numerous methods have been developed to produce nonlinear optically (NLO)-active polymeric films for such purposes. Ionic self-assembled multilayer (ISAM) films are a recently developed class of materials that allows detailed structural and thickness control at the molecular level, combined with ease of manufacturing and low cost. However, the layer-by-layer deposition technique utilized for this method currently requires lengthy processing times that challenge the feasibility of fabricating a thick film suitable for EO modulator device fabrication. This study focuses on addressing the influence of several pertinent processing variables affecting these challenges for application to electro-optic device fabrication. This study investigated (1) the effect of forced convection, varying deposition time and varying dye concentration on the properties of PAH/Procion Brown films fabricated via the hybrid reactive deposition scheme, (2) the automation and optimization of the fabrication of thick NLO active films and (3) the use of the hybrid covalent-electrostatic deposition scheme to fabricate a polymeric waveguide device with an electro-optic coefficient comparable to that of lithium niobate (LiNbO3). At fixed deposition time and concentration conditions, the presence of convection had little demonstrated effect on films with deposition times shorter than 2 minutes. For the 5 minute case, the presence of convection correlated with a ~45% increase in χzzz values and a 25% increase in absorbance per bilayer. At a constant dye concentration of 5 mg/ml, the deposition time had little effect on SHG for deposition times less than two minutes. In the presence of convection, the increase in deposition time from 2 minutes to 5 minutes showed a 57% increase in χzzz and a 30% increase in absorbance per bilayer. For a deposition time of 2 minutes in the presence of convection, the dye solution concentration was successfully reduced 5-fold (from 5 mg/ml to 1 mg/ml) with less than a 5% difference in χzzz, less than a 15% decrease in absorbance per bilayer and no detriment to film quality. These results strongly indicate that the deposition conditions remain well outside of the transport-limited regime at a dye concentration of 1 mg/ml. Rather, the surface reaction rate apparently is controlling. Depositing slides at an elevated temperature (~35°C), had an undetermined effect on χzzz, but showed a 15% increase in absorbance per bilayer. An automatic dipper was programmed to replicate the current manual deposition method to fabricate a film suitable for EO modulator devices. Utilizing the optimal conditions for the processing variables, an optically-homogeneous, 100 nm-thick film was fabricated utilizing the automated process, yielding a χzzz~ 23 x 10 esu. A three-layer coplanar electro-optic device was fabricated utilizing the hybrid reactive deposition method. For this device, the presence of added salt was found to increase the electrooptic coefficient r33 by a factor of 3 compared to its value when made with no added salt. The electro-optic coefficient of the added salt case was found to be about 1/2 that of lithium niobate (LiNbO3).
1 citations
TL;DR: In this article, the authors have studied the numerical analysis of the effect of Grashof number, modified Grashoff number and chemical reaction on the non-Darcy MHD flow of a Casson fluid over a nonlinearly stretching sheet in a porous medium.
Abstract: Received: 02/May/2019, Accepted: 07/Jun/2019, Online: 30/Jun/2019 Abstract: -In this paper, we have studied the numerical analysis of the effect of Grashof number , modified Grashof number and chemical reaction on the non-Darcy MHD flow of a Casson fluid over a nonlinearly stretching sheet in a porous medium. In the mathematical model, using similarity variables, the momentum , energy and concentration equations are transformed to non-dimensional ordinary differential equations.. And then these are solved numerically using bvp4c method, a Matlab inbuilt bvp4c-programm. A discussion for the effects of the parameters involved on the boundary layer regions and the magnitude of the velocity, temperature and concentration and Local skin friction , Local Nusselt Number and Local Sherwood Number have been done graphically and numerically using figures and tables.
1 citations
05 Nov 2020
TL;DR: In this paper, the authors investigated the habit change of L-Arginine doped KDP crystals in presence of constant d. c. electric field and found that the relative habit modification observedin the crystals grown under electric field is probably due to inclusion and adsorption of L -Arginines ions in the prismatic section of crystal.
Abstract: Potassium Dihydrogen Phosphate (KDP) is a non-linear optical (NLO) crystal well known over many years. Now-a-days it has become more popular because of its combination with organic materials forming new NLO material called semi-organics. We have investigated the habit change of L-Arginine doped KDP crystals in presence of constant d. c. electric field. Pure and L-Arginine (1 mol%) doped KDP crystals were grown with slow evaporation method at room temperature in presence as well as in absence of the electric field. The characteristics of the crystals obtained were studiedusing Fourier Transform Infrared (FTIR) spectroscopy, Second Harmonic Generation (SHG) efficiency test and Photoluminiscencespectra. The relative habit modification observedin the crystals grown under electric field is probably due to inclusion and adsorption of L-Arginine ions in the presence of electric field in the prismatic section of crystal. The FTIR spectra obtained of the crystalswere analyzedto identify functional groups present in the crystals. Photoluminescence spectra were used to assess presence of intrinsic impurities through color centres and to identify lattice defects. The SHG efficiency was found to have increased in the cases of both the doped crystals grown in presence of electric field and in absence of electric field.
1 citations
01 Sep 1988
TL;DR: The growth of single crystals of organic compounds by the Czochralski method is reviewed in this paper, where it is found that benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 10 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals.
Abstract: The growth of single crystals of organic compounds by the Czochralski method is reviewed. From the literature it is found that single crystals of benzil, a nonlinear optical material with a d sub 11 value of 11.2 + or - 1.5 x d sub 11 value of alpha quartz, has fewer dislocations than generally contained in Bridgman crystals. More perfect crystals were grown by repeated Czochralski growth. This consists of etching away the defect-containing portion of a Czochralski grown crystal and using it as a seed for further growth. Other compounds used to grow single crystals are benzophenone, 12-tricosanone (laurone), and salol. The physical properties, growth apparatus, and processing conditions presented in the literature are discussed. Moreover, some of the possible advantages of growing single crystals of organic compounds in microgravity to obtain more perfect crystals than on Earth are reviewed.
1 citations
TL;DR: A series of novel ionic chromophores consisting of a carbazole moiety and pyridinium rings connected by a double bond have been designed and synthesized as nonlinear optical materials as discussed by the authors.
Abstract: A series of novel ionic chromophores consisting of a carbazole moiety and pyridinium rings connected by a double bond have been designed and synthesized as nonlinear optical materials. Their linear and nonlinear optical properties were investigated by semiempirical calculation and experiment. The absorption maximum wavelengths (lmax) of these ionic chromophores showed shifting to longer wavelength region than their corresponding electrically neutral compounds. These ionic chromophores possess large first hyperpolarizabilities (b).
1 citations