Nonresonant third-order susceptibility measurements in the nematic liquid crystal K18
01 Mar 1993-Optical and Quantum Electronics (Kluwer Academic Publishers)-Vol. 25, Iss: 3, pp 157-162
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.
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TL;DR: In this article, the use of liquid crystals in different photonic components: optical filters and switches, beam-steering devices, spatial light modulators, integrated devices based on optical waveguiding, lasers, and optical nonlinear components are discussed.
Abstract: Liquid crystals are nowadays widely used in all types of display applications. However their unique electro-optic properties also make them a suitable material for nondisplay applications. We will focus on the use of liquid crystals in different photonic components: optical filters and switches, beam-steering devices, spatial light modulators, integrated devices based on optical waveguiding, lasers, and optical nonlinear components. Both the basic operating principles as well as the recent state-of-the art are discussed.
215 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: Low-power phase conjugation of azobenzene-compound-doped poly(methyl methacrylate) films was studied and it was shown that this kind of polymer has appreciable third-order optical nonlinearity.
Abstract: Push–pull azobenzene compounds were synthesized by the diazocoupling reaction, and low-power phase conjugation of azobenzene-compound-doped poly(methyl methacrylate) films was studied with a He–Ne laser at 632.8 nm. It is shown that this kind of polymer has appreciable third-order optical nonlinearity, with a χ(3) of approximately 10−4 esu in the tail of absorption.
15 citations
TL;DR: In this paper, azomethine derivatives were synthesized and their molecular structures were confirmed by nuclear magnetic resonance spectroscopy, Fourier transform infrared (FTI) and ultraviolet-visible spectrography.
Abstract: Liquid crystals of azomethine derivatives were synthesised and their molecular structures were confirmed by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy. Mesomorphic studies using differential scanning calorimetry, X-ray diffraction and polarising optical microscope revealed that all of these compounds exhibit thermotropic mesophases over a temperature range. The nonlinear optical properties of these liquid crystals were studied using a Z-scan technique with 7 ns pulse duration at 532 nm. The nonlinear refractive index, and the third order nonlinear susceptibility, were measured to be of the order of and respectively. Reverse saturable absorption was identified as the main mechanism responsible for optical limiting.
6 citations
References
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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
47 citations
TL;DR: In this article, a suspension of short graphite fibers was shown to provide an effective medium for nonlinear microwave interactions using a 18 GHz pump beam with up to 20 W continuous power, changes in the 94 GHz refractive index were measured by interferometry.
Abstract: A suspension of short graphite fibers was shown to provide an effective medium for nonlinear microwave interactions Using a 18‐GHz pump beam with up to 20 W continuous power, changes in the 94‐GHz refractive index were measured by interferometry The induced birefringence and anisotropic absorption indicate an alignment of the fibers with the electric field of the pump beam The resulting nonlinear refractive index coefficient of n2=26×10−4 cm2/W is of sufficient magnitude to demonstrate microwave bistability
35 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
TL;DR: Four-wave mixing from composite artificial Kerr media consisting of ellipsoidal microparticles suspended in a host liquid is discussed and calculations of nonlinear grating formation and decay times are given in a dynamic model.
Abstract: Four-wave mixing from composite artificial Kerr media consisting of ellipsoidal microparticles suspended in a host liquid is discussed. Calculations of nonlinear grating formation and decay times are given in a dynamic model that includes the effect of random collisions on the particulates. Phase-conjugate efficiencies for a model configuration are given as well as operating limits imposed by particulate scattering from the composite.
24 citations