Hologram writing in lithium niobate: Beam coupling and the transport length in the bulk photovoltaic effect

1979 ◽  
Vol 50 (6) ◽  
pp. 4201-4207 ◽  
Author(s):  
L. Young ◽  
M. G. Moharam ◽  
F. El Guibaly ◽  
E. Lun
Keyword(s):  
Lithium Niobate ◽  
Photovoltaic Effect ◽  
Transport Length ◽  
Beam Coupling

Optical Limiting with Lithium Niobate

1999 ◽  
Vol 597 ◽  
Author(s):  
Gary Cook ◽  
David C. Jones ◽  
Craig J. Finnan ◽  
Lesley L. Taylor ◽  
Tony W. Vere ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Diffusion Theory ◽  
Photovoltaic Effect ◽  
Optical Gain ◽  
Optical Limiting ◽  
Dark Conductivity ◽  
Simple Diffusion ◽  
Beam Coupling ◽  
Coupling Equations ◽  
Focusing Lens

AbstractIron doped lithium niobate (Fe:LiNbO3) in a simple focal plane geometry has demonstrated efficient optical limiting through two-beam coupling. The performance is largely independent of the total Fe concentration and the oxidation state of the Fe ions, providing the linear optical transmission of uncoated crystals is between 30% and 60%. Fe has been found to be the best dopant for LiNbO3, giving the widest spectral coverage and the greatest optical limiting. Optical limiting in Fe:LiNbO3 has been shown to be very much greater than predicted by simple diffusion theory. The reason for this is a higher optical gain than expected. It is suggested that this may be due to an enhancement of the space-charge field arising from the photovoltaic effect. The standard two-beam coupling equations have been modified to include the effects of the dark conductivity. This has produced a theoretical intensity dependence on the ΔOD which closely follows the behaviour observed in the laboratory. A further modification to the theory has also shown that the focusing lens f-number greatly affects the optical limiting characteristics of Fe:LiNbO3. A lens f-number of approximately 20 gives the best results.

Models for the bulk photovoltaic effect in ferroelectric crystals

1988 ◽  
Vol 66 (8) ◽  
pp. 649-654 ◽  
Author(s):  
Fayez El Guibaly
Keyword(s):  
Electron Transport ◽  
Spatial Frequency ◽  
Interference Pattern ◽  
Photovoltaic Effect ◽  
Hologram Recording ◽  
Optical Interference ◽  
Intensity Pattern ◽  
Transport Length ◽  
Beam Coupling ◽  
Optical Pattern

Three models for the bulk photovoltaic effect in electrooptic crystals are discussed. All models produce the same results. First, the photocurrent responsible for hologram storage is spatially shifted relative to the optical pattern that produced it. Second, the efficiency of hologram recording decreases with increases in the spatial frequency of the optical interference pattern. Third, the efficiency of hologram recording decreases for crystals exhibiting a strong bulk photovoltaic effect. The effect of finite electron transport length on volume-phase hologram storage is analyzed. It is shown that the resulting holograms are spatially shifted relative to the optical-intensity pattern that produced it. This phase shift affects beam coupling during hologram reading; it can be an aid in studying the bulk photovoltaic effect and the relative importance of the various mechanisms of hologram writing. The analysis also points out that the finite electron transport length reduces the ability of the crystal to store holograms if the spatial frequency of the optical interference pattern is increased.

scholarly journals Optofluidic Platform Based on Liquid Crystals in X-Cut Lithium Niobate: Thresholdless All-Optical Response

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 908
Author(s):  
Fabrizio Ciciulla ◽  
Annamaria Zaltron ◽  
Riccardo Zamboni ◽  
Cinzia Sada ◽  
Francesco Simoni ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Light Intensity ◽  
Lithium Niobate ◽  
Photovoltaic Effect ◽  
Optical Control ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Threshold Behaviour ◽  
All Optical

In this study, we present a new configuration of the recently reported optofluidic platform exploiting liquid crystals reorientation in lithium niobate channels. In order to avoid the threshold behaviour observed in the optical control of the device, we propose microchannels realized in a x-cut crystal closed by a z-cut crystal on the top. In this way, the light-induced photovoltaic field is not uniform inside the liquid crystal layer and therefore the conditions for a thresholdless reorientation are realized. We performed simulations of the photovoltaic effect based on the well assessed model for Lithium Niobate, showing that not uniform orientation and value of the field should be expected inside the microchannel. In agreement with the re-orientational properties of nematic liquid crystals, experimental data confirm the expected thresholdless behaviour. The observed liquid crystal response exhibits two different regimes and the response time shows an unusual dependence on light intensity, both features indicating the presence of additional photo-induced fields appearing above a light intensity of 107 W/m2.

Photovoltaic effect in a periodically poled lithium niobate Solc-type wavelength filter

2006 ◽  
Vol 88 (12) ◽  
pp. 121118 ◽  
Author(s):  
Lijun Chen ◽  
Jianhong Shi ◽  
Xianfeng Chen ◽  
Yuxing Xia
Keyword(s):  
Lithium Niobate ◽  
Photovoltaic Effect ◽  
Periodically Poled ◽  
Periodically Poled Lithium Niobate ◽  
Wavelength Filter

scholarly journals Hybrid photosensitive structures based on nematic liquid crystals and lithium niobate substrates

2018 ◽  
Vol 4 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Liana Lucchetti ◽  
Victor Reshetnyak
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Lithium Niobate ◽  
Nonlinear Optical ◽  
Photovoltaic Effect ◽  
Hybrid Structures ◽  
Liquid Crystal Films ◽  
Self Assembling ◽  
Crystal Films ◽  
Crystal Cells

Abstract Liquid crystal cells based on lithium niobate substrates have recently been proposed as good candidates for optofluidic devices and for light-induced controlled generation of defects in liquid crystal films. The peculiarity of these structures lies in the possibility of using the bulk photovoltaic effect of lithium niobate to obtain an optically induced dc field able to affect the molecular liquid crystal director. Reversible fragmentation and self-assembling of liquid crystal droplets driven by the lithium niobate pyroelectric properties have also been reported. We review the basic results obtained so far with the aim of making the point and seeing what else can be done in the framework of the realization of hybrid structures combining lithium niobate with the electro-optical and nonlinear optical properties of liquid crystals.

Contra-directional two-beam coupling by use of a single input beam in an iron-doped lithium niobate multimode fiber

2002 ◽  
Vol 41 (32) ◽  
pp. 6890 ◽  
Author(s):  
D. R. Evans ◽  
M. A. Saleh ◽  
T. J. Bunning ◽  
L. Lu ◽  
R. S. Meltzer ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Input Beam ◽  
Multimode Fiber ◽  
Beam Coupling ◽  
Iron Doped ◽  
Single Input
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