Nonresonant third order susceptibility measurements in a nematic liquid crystal‐PCH‐5
15 Aug 1992-Journal of Applied Physics (American Institute of Physics)-Vol. 72, Iss: 4, pp 1495-1497
TL;DR: In this paper, the real part of the third order nonlinear susceptibility χ(3) above the nematic to isotropic phase transition temperature of a nematic liquid crystal 4 (trans‐4'−4'n'n−pentylcyclohexy)‐benzonirtile (PCH‐5) from electro-optic Kerr effect experiments was determined.
Abstract: We report for the first time the determination of the real part of the third order nonlinear susceptibility χ(3)(−ω;ω,0,0) above the nematic to isotropic phase transition temperature of a nematic liquid crystal 4 (trans‐4’‐4’‐n‐pentylcyclohexy)‐benzonirtile (PCH‐5) from electro‐optic Kerr effect experiments. The value of χ(3) observed at 632.8 nm is found to be 6.2079×10−19 m2 V−2 close to the phase transition temperature at 55.1 °C.
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TL;DR: The current status of organic low-molecular weight and polymeric materials for third-order nonlinear optics is reviewed in this paper, where the importance of organic materials lies in their promise of large nonlinear optical figure of merit, high optical damage thresholds, ultrafast optical responses, architectural flexibility, and ease of fabrication.
Abstract: The current status of organic low-molecular weight and polymeric materials for third-order nonlinear optics is reviewed. The importance of organic materials lies in their promise of large nonlinear optical figure of merit, high optical damage thresholds, ultrafast optical responses, architectural flexibility, and ease of fabrication. Organic materials exhibiting interesting third-order nonlinear optical properties are discussed to illustrate the importance of structure–property correlations. Results on emerging organic materials that include liquids, dyes, fullerenes, charge-transfer complexes, π-conjugated polymers, dye-grafted polymers, organometallic compounds, composites, and liquid crystals are presented. Organic nonlinear optical materials seem promising for a wide range of applications and their potential for integrated optics should be further explored.
413 citations
TL;DR: In this article, a new tolane-base liquid crystal, 4'-heptyl-3-fluoro-4-isothiocyanatotolane (7TOLF), and a biphenyl-base nematogen, 7BF, have been investigated for the first time to determine their electro-optical behavior and third order non-linearity using the static Kerr effect method.
Abstract: A new tolane-base liquid crystal, 4'-heptyl-3-fluoro-4-isothiocyanatotolane (7TOLF), and a biphenyl-base nematogen, 4'-heptyl-3-fluoro-4-isothiocyanatobiphenyl (7BF), have been investigated for the first time to determine their electro-optical behaviour and third order non-linearity using the static Kerr effect method. Both the nematic compounds have a fluorine atom attached to the phenyl-NCS moiety. They possess the same polar head group (-NCS) and alkyl tail (-C7H15). So the effect of the tolane group of nematogen on the electro-optical behaviour was investigated and compared. The temperature dependence of the electric Kerr constant in the isotropic phase and the pre-transitional behaviour has been investigated for these high birefringence compounds in the isotropic phase. Both the compounds have a positive and large Kerr constant which increases with decrease in temperature. The Landau–de Gennes model was obeyed for these compounds. For 7TOLF, the observed value of susceptibility, χ3 is about 228 times higher than that of CS2. The experimental Kerr effect data were also compared with those of the well-studied nematic liquid crystals.
25 citations
TL;DR: The electrical and photoelectrical properties of aryl viologen (ArV), chemically known as 1,1′-diphenyl-4,4′-bipyridinium dichloride, in the form of thin film, sandwiched between ITO and In electrode were studied.
20 citations
TL;DR: In this article, a large nonresonant third-order nonlinear susceptibility, X(3) (-ω; ω, 0, 0) was observed in the isotropic phase of a nematic liquid crystal 4′-n-hexyl-4-cyanobiphenyl (K18).
Abstract: We have observed a large nonresonant third-order nonlinear susceptibility, X(3) (-ω; ω, 0, 0) in the isotropic phase of a nematic liquid crystal 4′-n-hexyl-4-cyanobiphenyl (K18). The highest value of X(3) obtained at 632.8 nm is 1.16274×10-18 m2V-2 corresponding to a temperature 29.3°C. The observed second-order pretransitional temperature T* from our measurements is 1.2°C below the first-order nematic to isotropic transition temperature. The dependence of the Kerr constant on (T-T*)-1 is found to be in good agreement with the predictions of the Landau-de Gennes model.
4 citations
TL;DR: In this paper, the real part of the third-order nonlinear susceptibility, x (3), was determined from electro-optic Kerr effect experiments in the isotropic phase of a nematic liquid crystal 4′-n-pentyl-4-cyanobiphenyl (K15).
Abstract: In this paper, we report for the first time the determination of the real part of the third-order nonlinear susceptibility, x (3)(−ω, ω, 0, 0), measurements in the isotropic phase of a nematic liquid crystal 4′-n-pentyl-4-cyanobiphenyl (K15) from electro-optic Kerr effect experiments. The value of x (3) obtained at 632·8 nm is found to be 1·08 × 10−18 m2 V−2 corresponding to a temperature 35·5°C and is the highest so far reported to the best of our knowledge.
2 citations
References
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TL;DR: In this paper, the authors measured the optical Kerr effect and the intensity-dependent ellipse rotation in order to study the pretransitional behavior of field-induced molecular alignment in the isotropic nematic substances.
Abstract: We have measured the optical Kerr effect and the intensity-dependent ellipse rotation in order to study the pretransitional behavior of field-induced molecular alignment in the isotropic nematic substances $p$-methoxy-benzylidene $p\ensuremath{-}n$-butylaniline (MBBA) and $p$-ethoxy-benzylidene-$p$-butylaniline (EBBA). The results agree well with predictions of the Landau---de Gennes model. Both the order-parameter relaxation time and the steady-state field-induced birefringence show critical divergence towards the isotropic \ensuremath{\rightarrow} nematic transition with a ${(T\ensuremath{-}{T}^{*})}^{\ensuremath{-}1}$ temperature dependence. In the case of MBBA, our results are also consistent with the results from light scattering, but the method we use is perhaps more straightforward and accurate. The nonlinear refractive indices and other relevant parameters of the materials are derived from the experiment.
135 citations
101 citations
TL;DR: A polar (PCH-5) and a non-polar (152) compound are introduced as liquid-crystalline bench-mark compounds in this article, which are affordable, stable, easy to handle and possess nematic mesophases between 30−54·9 and 24−103·4°C.
Abstract: A polar (PCH-5) and a non-polar (152) compound are introduced as liquid-crystalline bench-mark compounds. The materials chosen are affordable, stable, easy to handle and possess nematic mesophases between 30–54·9 and 24–103·4°C. All relevant macroscopic physical properties, such as refractive indices n o n e, dielectric permittivities ∥⊊, elastic constants K 11, K 22 and K 33, and bulk and rotational viscosities are given as a function of temperature, wavelength and frequency, when applicable. The reference compounds are available from E. Merck, Darmstadt.
56 citations
TL;DR: In this article, a new method was proposed for the determination of the electrooptic constants and relevant nonlinear susceptibilities of polycarbonate films doped with 4−diethylamino−4'−nitrostilbene.
Abstract: A new method is proposed for the determination of the electro‐optic constants and relevant nonlinear susceptibilities. It was applied to polycarbonate films doped with 4‐diethylamino‐4’‐nitrostilbene. The real and imaginary parts of the third‐order nonlinear susceptibility X(3) (−ω;ω, 0,0) of the film were determined by the method between 600 and 800 nm at room temperature. X(3) (−ω;ω, 0,0) is (6+4i)×10−12 esu or quadratic electro‐optic constant R is (−1−0.7i)×10−20 m2/V2 at 597 nm.
52 citations
TL;DR: In this paper, a laser induced optical birefringence was obtained for the first time in an anisotropic artificial Kerr medium, which consists of an aqueous suspension of dielectric microellipsoids which reorientate under electromagnetic and brownian torques.
26 citations