Introduction

Günter, Peter; Huignard, Jean‐Pierre

doi:10.1007/0-387-34081-5_1

Cited by 60 publications

(83 citation statements)

References 25 publications

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“…In 1966, Leith and Upatnieks gave a dramatic demonstration of how phase conjugation by holographic methods can counteract phase scrambling due to single scattering 8 . Optical phase conjugation has been achieved through holography, nonlinear optics 51 , Brillouin scattering 52 and the use of photorefractive crystals 53 . In 2008, Yaqoob and co-workers provided an implementation of phase conjugation for reversing wavefronts in biological tissue 54 .…”

Section: Using Spatial Degrees Of Freedom To Control Lightmentioning

confidence: 99%

Controlling waves in space and time for imaging and focusing in complex media

et al. 2012

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Section: Using Spatial Degrees Of Freedom To Control Lightmentioning

confidence: 99%

Controlling waves in space and time for imaging and focusing in complex media

et al. 2012

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“…For a long time, the latter were basically either photochromic or photorefractive crystals [1] or photosensitive polymers [2], which reached quite a mature state of development. The former offer typically excellent optical properties, thermal and temporal stability and allow the read-write option, but have a relatively low light-induced refractive-index modulation in the order of ≤

10^{- 4}

.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

et al. 2016

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A detailed investigation of the recording, as well as the readout of transmission gratings in composites of poly(ethylene glycol) dimethacrylate (PEGDMA) and ionic liquids is presented. Gratings with a period of about 5.8 micrometers were recorded using a two-wave mixing technique with a coherent laser beam of a 355-nm wavelength. A series of samples with grating thicknesses d0=10…150 micrometers, each for two different exposure times, was prepared. The recording kinetics, as well as the post-exposure properties of the gratings were monitored by diffracting a low intensity probe beam at a wavelength of 633 nm for Bragg incidence. To obtain a complete characterization, two-beam coupling experiments were conducted to clarify the type and the strength of the recorded gratings. Finally, the diffraction efficiency was measured as a function of the readout angle at different post-exposure times. We found that, depending on the parameters, different grating types (pure phase and/or mixed) are generated, and at elevated thicknesses, strong light-induced scattering develops. The measured angular dependence of the diffraction efficiency can be fitted using a five-wave coupling theory assuming an attenuation of the gratings along the thickness. For grating thicknesses larger than 85 microns, light-induced scattering becomes increasingly important. The latter is an obstacle for recording thicker holograms, as it destroys the recording interference pattern with increasing sample depth. The obtained results are valuable in particular when considering PEGDMA-ionic liquid composites in the synthesis of advanced polymer composites for applications, such as biomaterials, conductive polymers and holographic storage materials.

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“…It is interesting to note that the gain does not follow the same dependence on cell orientation as does the phase shift, despite the fact that the standard photorefractive two-beam coupling theory predicts that gain is directly proportional to sine of the phase shift. 21 The gain increased gradually and had a maximum value at an orientation angle of approximately 25°, for both directions of the cell rotation. This dependence did not show any dramatic changes around 0°orientation.…”

Section: B Two-beam Couplingmentioning

confidence: 93%

“…The maximum gain in this case is observed when the phase shift is equal to / 2, as reported earlier. 21 Figure 5 presents the results of the phase shift measurements versus the relative cell orientation. Except for the case of 0°, the phase shift was approximately equal to /2, namely, the optimum value to achieve high two-beam coupling gain.…”

Section: B Two-beam Couplingmentioning

confidence: 99%

The role of surface charge field in two-beam coupling in liquid crystal cells with photoconducting polymer layers

Kaczmarek

Dyadyusha

Slussarenko

et al. 2004

Journal of Applied Physics

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In liquid crystal cells with photoconductive poly͑N-vinlyl carbazole) polymer layers, an external dc field can be completely screened by surface charge layers that develop at the liquid crystalpolymer interface. Under spatially modulated illumination, surface charge layers can be discharged in bright areas and lead to reorientation and spatially modulated Freedericksz transition. As a result, an asymmetric energy exchange in the photorefractive two-beam coupling process can take place. We propose a model to explain the origin of reorientation and phase shift in the two-beam coupling process, based on the profile and tilt of the refractive index grating. We also show that cells with just one photoconducting layer are more efficient than a typical design with two layers.

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Introduction

Cited by 60 publications

References 25 publications

Controlling waves in space and time for imaging and focusing in complex media

Controlling waves in space and time for imaging and focusing in complex media

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

The role of surface charge field in two-beam coupling in liquid crystal cells with photoconducting polymer layers

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