Effect of Optical Nonlinearity Dynamical Enhancement in Dye Doped Liquid Crystal Under A Electrical Field

Agashkov, A. V.; Kovalev, A. A.; Serak, Svetlana V.; Parka, Janusz

doi:10.1080/10587250210565

Cited by 9 publications

(8 citation statements)

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“…Investiga− tions of dynamic light scattering originated from electri− cally induced instabilities [40] have shown that the cell ir− radiation by low power beam (< 1 mW) of nonpolarized cw He−Ne laser results in the domain structure ordering. We observed pulsed enhancement of the degenerate wave mixing efficiency by two orders in Raman−Nath regime that arises from resonant interaction between optical inter− ference field and instabilities excited in LC cell by exter− nally applied ac electric voltage [41]. In particular, we ob− tained peak phase−conjugated reflectivity in degenerate four−wave mixing (DFWM) of as much as 800%.…”

Section: Introductionmentioning

confidence: 75%

“…The total input power density of the writing beams is~30 mW/cm 2 . The crossing angle q be− tween two writing beams and the LC cell tilting angle a were chosen to satisfy "angular resonance" [41]. LC cell is connected to the DC and polarity reversal AC voltage power supply.…”

Section: Resultsmentioning

confidence: 99%

“…The resulting polymer layers of 0.12-0.16−μm thickness were rigidly rubbed to ob− tain a planar orientation of NLC with pretilt angle of~10°. The cells were filled with a nematic 4−trans−4'−n−hexyl− −cyclohexyl−isothiocyanatobenzene (6CHBT) activated by anthraquinone dyes AD−1 and AD−2 (with the absorption coefficients a || = 3300 cm -1 , a^= 800 cm -1 ) [41]. The LC 6CHBT has a positive dielectric anisotropy De = 8 with the static permittivity components e || = 12.0 and e^= 4.0.…”

Section: Resultsmentioning

confidence: 99%

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Investigations of dynamic photorefractivity regime by optical polarizing microscopy

Agashkov

Kovalev

Parka

2009

Opto-Electronics Review

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We present a technique, based on optical polarizing microscopy, and results of direct observation of the optical interference field effect on the transient domains excited by ac electric field in a nematic planar cell with photosensitive aligning layers. The light source used in a microscope operated in DC mode as well as in triggered pulse one. Obtained microscopic snapshots of transient domain structure confirmed our assumption of the transient domains reordering (trapping) by the low intensity optical interference field.

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Section: Introductionmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Investigations of dynamic photorefractivity regime by optical polarizing microscopy

Agashkov

Kovalev

Parka

2009

Opto-Electronics Review

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“…It is known that at dc voltage applied to a LC cell the efficiency of the wave mixing increases monotonically with cell tilting angle b increasing from the bisector of the writing beams up to b = 45º 3 . Another type of diffraction efficiency was observed at ac voltage applied to a LC cell, so called "angular resonance" 4 . Numerous papers dealing with the diffraction of Raman-Nath type at tilted geometry have been published.…”

Section: Introductionmentioning

confidence: 99%

Index grating surface anchoring

Agashkov¹,

Kovalev²,

Parka

2005

SPIE Proceedings

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A simple model describing location of Raman-Nath index grating photoexcited in a planar cell with photoconductive orienting layers is proposed. We believe that index grating vector is parallel to cell boundaries. One of the most important features resulting from this model is that the index grating spacing equals to projection of the exciting optical grating spacing on cell boundaries. The experimental study was carried out with 9 micrometer thick planar cell filled with nematic liquid crystal 6CHBT, activated by anthraquinone dyes. DC or square-wave AC field has been applied to the cell. Holographic gratings were recorded by two (signal + pump) or three (signal + 2 pumps) coherent p-polarized beams from He-Ne laser operating at 632.8 nm. The crossing angle between signal and pump beams and the sample tilting angle were chosen to satisfy "angular resonance". The tilting angle varied from 20º to 45º, high diffraction orders were observed up to angle 77º. Calculations on the basis of our model and experimental results are in good agreement. We also discuss and present explanation of the observed effects in geometry with 2 pump beams.

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“…Investigation of the light scattering from induced instabilities [1] showed that irradiation of a cell by a cw He-Ne laser with a power <1 mW leads to ordering of the domain structure. At the resonant interaction between the instabilities excited in an LC cell by an external ac electric field and the optical interference field, a stepwise increase in the efficiency of degenerate wave mixing by two orders of magnitude was observed [2]. In the scheme of degenerate four-wave mixing (DFWM) with phase conjugation, the maximum value of the phaseconjugate reflection coefficient R in the pulse was 800%.…”

Section: Introductionmentioning

confidence: 99%

10.1007/s11445-008-2020-4

2010

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The dynamic photorefractivity in a cell with photoconducting orienting layers, filled with a nematic liquid crystal (LC) 6CHBT and a mixture of anthraquinone dyes AD1 and AD2, has been investigated. The single-pulse mode, in which the polarity and amplitude of a dc electric field applied to an LC cell are switched for a fixed time interval, has been used. The scheme of dynamic self-diffraction of low-power laser beams was used in the experiment. The dependences of the width and intensity of diffraction pulses on the bias and switching voltages have been investigated. It is established that the width and intensity of the diffraction pulse arising after initial voltage recovery depends also on the switching pulse width. At the optimal width of the control pulse, the diffraction efficiency increases by two orders of magnitude.

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Effect of Optical Nonlinearity Dynamical Enhancement in Dye Doped Liquid Crystal Under A Electrical Field

Cited by 9 publications

References 0 publications

Investigations of dynamic photorefractivity regime by optical polarizing microscopy

Investigations of dynamic photorefractivity regime by optical polarizing microscopy

Index grating surface anchoring

10.1007/s11445-008-2020-4

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