27 August 2008 Liquid crystal based electro-optic Bragg gratings for laser beam attenuations
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Abstract
This paper provides research progress in the development of fast electro-optic gratings based on liquid crystals for laser beam attenuations. The electro-optic phase grating is formed by the phase separation of ~100nm liquid crystals droplets from a polymerizing organic matrix using holographic interference technique. The formed grating separates the incident laser beam into the output beams: the transmitted and diffracted beam, whose intensities can be electrically adjusted through electro-optic effect. The fast electro-optic gratings have a very fast electro-optic response time of 50 microseconds with diffraction efficiency above 99.8%. Optical receivers used in FSO have a limited dynamic range and there is a need for in-line variable attenuators to keep the signal levels from overloading the receiver. These attenuators should be continuous, provide sufficient attenuation, and also provide a low insertion loss for weak signal reception. The use of electro-optic Bragg gratings is one solution to meet the requirements for an in-line attenuator for FSO.
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James Foshee, Brian Stadler, Suning Tang, Yuanji Tang, Jennifer Colegrove, "Liquid crystal based electro-optic Bragg gratings for laser beam attenuations", Proc. SPIE 7050, Liquid Crystals XII, 70500W (27 August 2008); doi: 10.1117/12.796208; https://doi.org/10.1117/12.796208
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