Керування інтенсивністю лазерного випромінювання у рідкокристалічних вентилях при записі об’ємної динамічної ґратки

• Date: 2023
• Main Authors: Mystetskyi, V., Bugaychuk, S.
• Format: Article
• Language: English; Ukrainian
• Published: Publishing house "Academperiodika" 2023
• Subjects: нематичнi рiдкi кристали; двопучкова взаємодiя; динамiчнi ґратки; дифракцiйна ефективнiсть
• Online Access: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2023147
• Journal Title: Ukrainian Journal of Physics

Experimental studies of dynamic holography in pure nematic liquid crystals (NLCs) confirm the recording of dynamic gratings not only in NLC cells with homeotropic orientation, but also in planar ones. The explanation can be found on the basis of the photorefractive mechanism of grating recording, which is characterized by the formation of an unbalanced charge at the cell substrate surface under the action of spatially inhomogeneous light beams. The emergence of an internal tangential electric field (along the cell substrate) together with an external electric field applied normally to the cell substrates makes it possible to control the direction of the net electric field vector. In this paper, a model describing how the intensities of laser beams change at their self-diffraction and diffraction at a dynamic grating generated in the NLC has been developed and analyzed. The dynamic phase grating appears due to the orientation mechanism of birefringence in the NLC at the mixing of two laser beams that form a spatially periodic interference pattern of the acting light field. The results of calculations of the output laser beam intensities in the first self-diffraction and diffraction orders are in good agreement with experimental data. In particular, they explain a well-pronounced maximum in the dependence of the diffraction efficiency on the external applied voltage.