Growth and holographic characterization of nonstoichiometric sillenite-type crystals

Vogt, H.; Buse, K.; Hesse, H.; Krätzig, E.; García, R. Ramos

doi:10.1063/1.1400095

Cited by 31 publications

(17 citation statements)

References 25 publications

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“…The polarization plane rotation is very slightly influenced, since n ӷ in the spectral range of 460-760 nm (Refs. [22][23][24] and, most importantly, the gradient ⌬ / ⌬E is not influenced at all. The experimental value of the electrogyration coefficient at 640 nm that we found ͑ = 0.1 pm/ V͒ is within the boundary Ͻ 0.35 pm/ V at 633 nm reported by Vachss and Hesselink 17 for BGO.…”

Section: Resultsmentioning

confidence: 95%

“…3) is related to the dispersion observed in optical activity and refractive index near the absorbtion edge which is found to be about 3.2 eV. 22 The electrogyration dispersion has been studied in scheelite and apatite crystals 10,25 only, and has not been detected before in sillenite crystals. 14 According to the microscopic theory of electrogyration by Stasyuk and Kotsur 26 the lattice and ionic contribution to the effect are studied with the help of Green's functions.…”

Section: Resultsmentioning

confidence: 99%

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Direct measurement of the dispersion of the electrogyration coefficient of photorefractive Bi12GeO20 crystals

Deliolanis

Kourmoulis

Asimellis

et al. 2004

Journal of Applied Physics

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We report on the direct measurement of the electrogyration coefficient of Bi 12 GeO 20 sillenite crystals over the visible spectral range. The coefficient is directly measured on a (111)-cut crystal for which the electro-optic and electrogyratory effects are decoupled. The precision of the measurement method over various parameters including absorption and misorientation is examined. The value of the electrogyration coefficient is found to vary from 0.37± 0.03 to 0.05± 0.01 pm/ V for the 460-760-nm spectrum range, which is within the upper boundaries that have been specified in previous experiments. It is also found that the electrogyration coefficient follows the dispersion law of optical activity and refractive index.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Direct measurement of the dispersion of the electrogyration coefficient of photorefractive Bi12GeO20 crystals

Deliolanis

Kourmoulis

Asimellis

et al. 2004

Journal of Applied Physics

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“…Bi 12 GeO 20 is a well-known electrooptic crystal with the Pockels coefficient 41 crystal is photorefractive and so can be used for optical storage (see, e.g., [13]). The experimental techniques employed while studying the optical indicatrix rotation and observing the helical mode have been described in detail in our recent works [10,11].…”

Section: Resultsmentioning

confidence: 99%

On the spin-to-orbit momentum conversion operated by electric field in optically active Bi12GeO20 crystals

Vasylkiv¹,

Krupych²,

Skab³

et al. 2011

Ukr. J. Phys. Opt.

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Abstract. An optical conversion of spin angular momentum to orbital angular momentum (SAM-to-OAM) that appears in Bi 12 GeO 20 crystals under the effect of conically shaped external electric field due to a Pockels effect has been studied both experimentally and theoretically. We have revealed the appearance of a doughnut mode and an optical vortex in the system consisting of a right-handed circular polariser, a sample subjected to conical electric field, and a left-handed circular analyser. It has been found that the presence of natural optical activity leads to notable decrease in the efficiency of the SAM-to-OAM conversion.

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“…Besides, the above crystal is photorefractive and so can be used in optical 52 storage devices (see, e.g., [7]). We prepared a crystalline plate perpendicular to the direction <111>, with the thickness of 6 mm.…”

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confidence: 99%

Appearance of spiral patterns at the interference of spherical and vortex-bearing waves in the cases of torsion- and electric field- induced vortices in crystals

Vasylkiv¹,

Skab²,

Vlokh³

2012

Ukr. J. Phys. Opt.

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Abstract. Basing on interference experiments, we have proved that both torsion of crystals around their three-fold symmetry axis and application of conically shaped electric field to crystals lead to the appearance of singly charged vortex beam. A spiral-like interference pattern has been observed in the conditions of torsion of LiNbO 3 crystals and application of conically shaped electric field to Bi 12 GeO 20 crystals.Keywords: optical vortex, interference, torsion PACS: 42.50.Tx, 78.20.Jq, 78.20.hb, 42.25.Hz UDC: 535.543, 535.55, 538.945.5, 548.1.022 In our recent works [1,2] we have shown that torsion of crystals produces a singly charged vortex when a circularly polarized optical wave propagates along the torsion axis. This phenomenon can be observed in optically uniaxial crystals belonging to triginal system or in cubic crystals under torsion around three-fold symmetry axis [2]. We have also demonstrated [3][4][5] that the same singly charged vortex appears when a conically shaped electric field is applied to the crystals along their three-fold or six-fold inverse symmetry axes. The appearance of a doughnut mode in the both cases has been experimentally proved by detecting specific spatial distribution of optical indicatrix orientation around the vortex core (or the axis of twisting). Namely, the optical indicatrix is rotated by the angle / 2 Z    whenever the tracing angle changes by  . However, the commonly accepted proof for a helical mode is observation of spiral-or fork-like patterns in cases of its interference with spherical or plane waves, respectively. In the present work we will show that the spiral interference patterns do appear in the mentioned experiments, provided that the vortex-bearing mode is induced by torsion in LiNbO 3 crystals or by electric field in Bi 12 GeO 20 crystals. A sample of LiNbO 3 (the point symmetry group 3m) used in our experiments was prepared in the shape of octahedral prism, with its lateral faces parallel to Z axis and the basis parallel to XY plane. The sample had the size of 13 mm along the optic axis Z and the thickness of 6 mm between the lateral faces. The YZ plane was accepted to be parallel to one of the symmetry mirror planes. A light of He-Ne laser (the wavelength of 632.8 nm   ) propagated along the Z axis. Torsion torques M z were applied to one of the base faces of the crystalline prism, while the opposite base face was kept fixed. Cubic crystals of Bi 12 GeO 20 represent a well-known electrooptic material, with the Pockels coefficient 41 3.5 pm/V r  and the refractive index n = 2.55 for the wavelength 632.8 nm  [6].The material possesses a notable optical activity effect (the specific optical rotation is equal to =20 deg/mm [6]). Besides, the above crystal is photorefractive and so can be used in optical

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Growth and holographic characterization of nonstoichiometric sillenite-type crystals

Cited by 31 publications

References 25 publications

Direct measurement of the dispersion of the electrogyration coefficient of photorefractive Bi12GeO20 crystals

Direct measurement of the dispersion of the electrogyration coefficient of photorefractive Bi12GeO20 crystals

On the spin-to-orbit momentum conversion operated by electric field in optically active Bi12GeO20 crystals

Appearance of spiral patterns at the interference of spherical and vortex-bearing waves in the cases of torsion- and electric field- induced vortices in crystals

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