Role of Temperature in Controlling Performance of Photorefractive Organic Glasses

Ostroverkhova, Oksana; He, Meng; Twieg, Robert J.; Moerner, W. E.

doi:10.1002/cphc.200200633

Cited by 46 publications

(71 citation statements)

References 71 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The improvement of existing organic NLO materials and the design of novel materials involve two major steps on both microscopic and macroscopic levels:…”

Section: Introductionmentioning

confidence: 99%

Macroscopic Order and Electro‐Optic Response of Dipolar Chromophore–Polymer Materials

2004

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This Minireview considers the key factors that govern the organization of macroscopic polarization in nonlinear optical systems obtained by electric poling of organic dipolar chromophores dissolved in polymer matrices. The macroscopic electric polarization depends on the thermodynamic state of the dipole system. The dependence of the paraelectric and antiferroelectric states of dipolar chromophores on the chromophore concentration and the strength of the poling field is discussed. Phase transitions between the para- and antiferroelectric states are investigated within the limits of the Ising and isotropic models for the chromophore dipoles and are considered for varying chromophore concentration, poling field strength, and macroscopic shape of the sample used for poling. The macroscopic polarization and electro-optic coefficient of the material change drastically upon phase transition. The theories are compared with the experimental data on the electro-optic coefficient dependence on the chromophore concentration. The isotropic dipole model shows excellent agreement with experiment for the chromophore systems most commonly used in nonlinear optics.

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Section: Introductionmentioning

confidence: 99%

Macroscopic Order and Electro‐Optic Response of Dipolar Chromophore–Polymer Materials

2004

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“…[5,29] It is evident from Equation (3) that a higher value of N T causes a higher value of E q which corresponds to a higher value of E SC and hence of G 2 . The great importance of the traps is now manifest even if many questions have still to be clarified on the real nature and behaviour of the traps.…”

Section: Photorefractivity Measurementsmentioning

confidence: 95%

“…[7] A satisfactory explanation can be given starting from the already cited concept of "traps". [5,29] A trap can be defined as a site of the material in which the electrostatic potential is sufficiently deep so that it can capture one migrating photocharge. All stopped charges give origin to the charge lattice that in turn generates the space-charge field E SC .…”

Section: Photorefractivity Measurementsmentioning

confidence: 99%

“…[1,2] In more recent years, the photorefractive effect, initially discovered in inorganic materials, has been particularly studied in organic molecular substrates both as neat material (low molecular weight organic glass formers, LMWG) and as blends in which the PR chromophore is dissolved in different organic matrices or polymers. [3][4][5] Organic PR materials offer the advantage that their molecular components can be largely selected and modified to obtain specific electrooptical characteristics. The electro-optical parameters of a given selected chromophore-the electric dipole moment (edm), the polarizabilities a and b, and the first-and secondorder susceptibilities-that determine the efficiency of the photorefractivity, can today be computed.…”

Section: Introductionmentioning

confidence: 99%

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The Relevance of the Collaborative Effect in Determining the Performances of Photorefractive Polymer Materials

Angelone¹,

Ciardelli²,

Colligiani³

et al. 2010

ChemPhysChem

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A derivative of 2-methylindole, 3-[2-(4-nitrophenyl)ethenyl]-1-allyl-2-methylindole, NPEMI-A, is studied for its photoconductivity and photorefractivity behaviour. Its blends with the organic polymer poly-(2,3-dimethyl-N-vinylindole), PVDMI, are also investigated. Due to the expected and devised mutual solubility of the two components of the blends, it is possible to carry out measurements with the weight percent of the chromophore NPEMI-A changing from zero to 100. Films were produced by a squeezing process between two ITO-covered glass sheets. No opacity phenomena, that are so common for many other organic blends due to the segregation of the dissolved chromophore, are observed. The photorefractive optical gain Gamma(2) is obtained as a function of the chromophore content. Differential scanning calorimetry measurements (DSC) are also carried out to obtain the whole change of the glass transition temperature T(g) as a function of the amount of chromophore contained in the blends. From the experimental trend of T(g) a meaningful quantitative estimate of the value of the electrostatic interactions acting in the studied blends, is obtained. The importance of the value of T(g), and of the electrostatic interactions, in determining the extent of the photorefractivity is clearly evident. The results are compared for NPEMI-A (Gamma(2) = 210 cm(-1)) and for NPEMI-E (Gamma(2) approximately = 2000 cm(-1)) that has a N-2-ethylhexyl group instead of a N-allyl group. The Pockels and Kerr contributions and--for the first time--a "collaborative effect" of the photorefractivity of NPEMI-A are distinguished and quantitatively evaluated.

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“…To the best of our knowledge, only one organic LMW glass was demonstrated to exhibit holographic response times in the sub-second time domain (DRDCTA, [ 193 ] ) which is clearly inferior to performance reached by the composite approach. This may either be due to orientational limitations and thus the T g of the material [ 191 ] or to the photoconductivity of the materials. [ 112 ] Another problem of LMW-materials is high losses due to beam-fanning.…”

Section: Multifunctional Materials/organic Lmw-glassesmentioning

confidence: 97%

Organic Photorefractive Materials and Applications

2011

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This review describes recent advances and applications in the field of organic photorefractive materials, an interesting area in the field of organic electronics and promising candidate for various aspects of photonic applications. We describe the current state of knowledge about the processes involved in the formation of photorefractive gratings in organic materials and focus on the chemical and photo‐physical aspects of the material structures employed in low glass‐transition temperature amorphous composites and organic photorefractive glasses. State‐of‐the art materials are highlighted and recent demonstrations of photonic applications relying on the reversible holographic nature of the photorefractive materials are discussed.

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Role of Temperature in Controlling Performance of Photorefractive Organic Glasses

Cited by 46 publications

References 71 publications

Macroscopic Order and Electro‐Optic Response of Dipolar Chromophore–Polymer Materials

Macroscopic Order and Electro‐Optic Response of Dipolar Chromophore–Polymer Materials

The Relevance of the Collaborative Effect in Determining the Performances of Photorefractive Polymer Materials

Organic Photorefractive Materials and Applications

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