Space charge field limitations in photorefractive LiNbO3:Fe crystals

Rupp, R. A.; Sommerfeldt, R.; Ringhofer, K. H.; Krätzig, E.

doi:10.1007/bf00348974

Cited by 29 publications

(2 citation statements)

References 35 publications

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“…The doped congruent crystals all present values of σ ph intermediate between the two cases, falling in the range of 10 -11 (Ωm) -1 . It is interesting to note that, in contrast with the case of iron-doped crystals [21] and pure congruent crystals, the doped crystals we have studied present values of the dark conductivity comparable with those of the photoconductivity at low intensities (100W/cm 2 ). We have also started to investigate the dependence of photoconductivity on the light intensity.…”

Section: Resultsmentioning

confidence: 85%

High-photorefractive resistance of hafnium-doped, single-domain, and periodically-poled lithium niobate crystals

Degiorgio¹,

Kokanyan²,

Razzari³

et al. 2004

SPIE Proceedings

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Transient and steady-state measurements of photo-induced birefringence variations in single domain and periodically poled lithium niobate (LN) crystals containing different non-photorefractive impurities are presented. The birefringence change is induced by a 532-nm laser beam in the intensity range 0-500 W/cm 2 , and is probed by 632.8-and 1523-nm beams. Data were taken at 25 and 50°C. We find that HfO 2 doping is very effective in reducing the photorefraction. This is interesting also because it is known that Hafnium-doped LN crystals can be periodically-poled during growth. The analysis of the rise and decay of the induced birefringence shows that doping considerably increases both the photoconductivity and the dark conductivity of the LN crystals.

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Section: Resultsmentioning

confidence: 85%

High-photorefractive resistance of hafnium-doped, single-domain, and periodically-poled lithium niobate crystals

Degiorgio¹,

Kokanyan²,

Razzari³

et al. 2004

SPIE Proceedings

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“…Note that the presence of the phase shift in both cells confirms that the optical gain is real and is not an artefact of the strong diffraction efficiency in the cells. Because there is no coupling in either cell design without applying a voltage, charge diffusion must be negligible and the phase shift is most probably due to saturation of the space charge field giving rise to a non-sinusoidal index grating in a similar manner to the photovoltaic effect in Fe:LiNb03 [3][4][5][6].…”

Section: Discussionmentioning

confidence: 97%

<title>Transversely excited liquid crystal cells</title>

2002

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The integration of photorefractive liquid crystal beam coupling devices into optical systems is often hampered by the need to tilt the liquid crystal cells to high angles of incidence in order to obtain efficient beam coupling. Owing to poor charge diffusion in most liquid crystal systems, charge migration depends mainly on an externally applied drift field. Conventional cells, with electrodes applied to the surfaces of the windows, therefore need to be tilted with respect to the incident light to enable a component of the applied electric field to appear along the direction of the optical grating k-vector. This paper reports on an alternative design in which the electric field is applied transversely, enabling devices to be presented at normal incidence to the system optical propagation direction. We demonstrate the optical gain from transversely excited homeotropic liquid crystal cells is very similar to that obtainable with conventional homeotropic cells, with the added unexpected advantage of an order of magnitude increase in speed.

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Influence of zinc doping on the photorefractive properties of lithium niobate

Simon

Jermann

Volk

et al. 1995

Phys. Stat. Sol. (a)

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The photorefractive properties of lithium niobate crystals containing zinc dopants as well as iron ions are studied to obtain quantitative information on the influence of Zn. Elementary holographic gratings are recorded and erased using light intensities from 102 to about 1011 W/m2. The experiments indicate that nonlinear contributions to the bulk photovoltaic effect and to the photoconductivity as well as light‐induced absorption changes at high intensities can be diminished by Zn doping. Additionally, Zn dopants considerably increase the photoconductivity and thus reduce light‐induced refractive index changes. Results are discussed using a two‐center charge transport model recently proposed to describe the photorefractive properties of LiNbO3:Fe at high light intensities.

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Space charge field limitations in photorefractive LiNbO3:Fe crystals

Cited by 29 publications

References 35 publications

High-photorefractive resistance of hafnium-doped, single-domain, and periodically-poled lithium niobate crystals

High-photorefractive resistance of hafnium-doped, single-domain, and periodically-poled lithium niobate crystals

<title>Transversely excited liquid crystal cells</title>

Influence of zinc doping on the photorefractive properties of lithium niobate

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