Strongly non-linear optical ferroelectric liquid crystals for frequency doubling

Schmitt, K.; Herr, Rolf‐Peter; Schadt, M.; Fünfschilling, J.; Buchecker, Richard; Chen, X. H.; Benecke, C.

doi:10.1080/02678299308027712

Cited by 77 publications

(21 citation statements)

References 13 publications

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“…1 implies a lower bound for d eff of Ϸ4.5 pm/V, which, in Ϸ3 h rises to 5.0 pm/V. We also conclude that the SHG in the K phase arises purely from the second order susceptibility, i.e., there is no contribution from electric field-induced SHG due to (3) . Figures 2 and 3 present the quite distinct dependence of d eff sinc͑⌬kL͒/n 3/2 on in the SmC* ͑Tϭ42°C, E 0 ϭ12 V/m͒ and K phases ͑Tϭ37°C, E 0 ϭ0 V/m͒, respectively, for 2 ϭp and s. As Eq.…”

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confidence: 75%

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Large and stable second harmonic generation in a crystalline phase of a ferroelectric liquid crystal

Sprunt

Naciri

Ratna

et al. 1995

Applied Physics Letters

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Second harmonic generation (SHG) has been studied in a nitro-substituted ferroelectric liquid crystal cooled from the smectic-C* into a three-dimensional crystalline (K) phase in an applied electric field. The SHG efficiency in the K phase is found to be deff≳4.5 pm/V, about 25 times the value in the SmC* phase, and, unlike the SmC* case, remains constant in zero field for ≳25 h. A quantitative analysis of the polarization dependence of the SHG reveals that the dominant d coefficients contributing to the measured signal differ for the two phases, and that the orientation of the liquid-crystal director in the K phase is modulated in one dimension.

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confidence: 75%

“…[1][2][3] These chiral materials are noncentrosymmetric in the smectic-C* ͑SmC*͒ phase (C 2 point symmetry͒. They thus possess a finite second order NLO susceptibility i jk (2) , which, in the case of second harmonic generation ͑SHG͒, is commonly expressed in terms of the contracted tensor 4 d i j .…”

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confidence: 99%

Large and stable second harmonic generation in a crystalline phase of a ferroelectric liquid crystal

Sprunt

Naciri

Ratna

et al. 1995

Applied Physics Letters

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“…The key result of our earlier work 6 was the achievement of an effective susceptibility d eff Ϸ4.5 pm/V ͑the highest value reported to date in a chiral liquid crystal͒, using a molecule whose intrinsic ␤ is, however, considerably less than that attained by recent synthesis efforts. 4 The value of d eff was stable without the need for surface stabilization ͑i.e., very narrow sample cells͒ or for applied fields. In the following, we present new results from optical microscopy and x-ray scattering which confirm that the low temperature structure is a molecular crystal and reveal that the molecular orientation frozen in the crystal is spatially modulated on a macroscopic length scale, an effect which may depend on the history of the applied electric field.…”

Section: Introductionmentioning

confidence: 98%

“…These materials, which are generally far easier and cheaper to process than inorganic crystals and which offer a high degree of integrability into optoelectronic devices, may be broadly classified into two categories: inherently isotropic systems like glassy polymers doped with or bonded to hyperpolarizable molecules, 1 which must be aligned by large external fields to show a bulk second-order NLO susceptibility, and mesogenic systems, such as chiral liquid crystals [2][3][4] and organic molecular crystals, where the susceptibility arises spontaneously from the broken symmetry of an ordered mesophase. In general, a nonzero macroscopic susceptibility d arises from a combination 1,5 of constituent molecules which have electric field-induced dipole moments ͑giving rise to a second-order molecular susceptibility ␤͒ and a collective structure wherein, on average, the individual dipoles are oriented so that the system lacks mirror symmetry, or is noncentrosymmetric.…”

Section: Introductionmentioning

confidence: 99%

Large second-order optical nonlinearity in a molecular crystal formed from a chiral smectic liquid crystal

Sprunt

Geer

Crawford

et al. 1998

Journal of Applied Physics

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Articles you may be interested inLinear and second-order nonlinear optical properties of ionic organic crystals Investigation of the linear and second-order nonlinear optical properties of molecular crystals within the local field theory Large second-order optical nonlinearity in a ferroelectric molecular crystal of croconic acid with strong intermolecular hydrogen bonds Large second-order optical nonlinearities of fresnoite-type crystals in transparent surface-crystallized glasses J. Appl. Phys. 95, 3503 (2004); 10.1063/1.1664022Tensor analysis of the second-order nonlinear optical susceptibility of chiral anisotropic thin films A new approach to achieving a large second-order nonlinear optical susceptibility in a chiral liquid crystal is described. This approach uses an aligned smectic-C* liquid crystal as a template for forming a molecular crystal, which freezes out the rotation of the molecular dipoles and thereby greatly enhances the noncentrosymmetric order of the structure. Analysis of the measured second harmonic generation gives maximum values of individual susceptibility components of ϳ25 pm/V, which are stable when the field is removed.

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“…The first approaches to the design of NLO FLCs used normal calamitic mesogens [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Second-harmonic generation in a laterally azo-bridged trimer ferroelectric liquid crystal: Phase matching in the presence of a helicoidal structure

et al. 2012

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Optical second-harmonic generation (SHG) has been studied in a trimer smectic C* liquid crystal especially designed for nonlinear optical applications. The molecule has a long conjugated donor-acceptor unit that transversally links three parallel rod-shaped moieties. A strong SHG signal has been observed at a fundamental wavelength of 1369 nm even in the presence of the spontaneous helicoidal structure of the smectic C* phase.This unusual behavior has been interpreted as due to the existence of a phase matching, in which the wave vector mismatch is compensated by the wave vector of the helix. This point has been confirmed by the study of the SHG intensity versus sample thickness and light polarization characteristics. The main coefficient of the second-order susceptibility tensor of the material has been estimated to be d 22 =28 pm/V.

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Strongly non-linear optical ferroelectric liquid crystals for frequency doubling

Cited by 77 publications

References 13 publications

Large and stable second harmonic generation in a crystalline phase of a ferroelectric liquid crystal

Large and stable second harmonic generation in a crystalline phase of a ferroelectric liquid crystal

Large second-order optical nonlinearity in a molecular crystal formed from a chiral smectic liquid crystal

Second-harmonic generation in a laterally azo-bridged trimer ferroelectric liquid crystal: Phase matching in the presence of a helicoidal structure

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