Diffraction grating induced with electric field of p n junction in nematic cell

Author(s):  S.I. Bogdanov, Belgorod National Research University, Belgorod, Russia, kucheev@.bsu.edu.ru

V.A. Gudkova, Belgorod National Research University, Belgorod, Russia

D.A. Kolesnikov, Belgorod National Research University, Belgorod, Russia

S.I. Kucheev, candidate of Sciences, associate Professor, Belgorod National Research University, Belgorod, Russia, kucheev@.bsu.edu.ru

A.A. Pleskanev, Belgorod National Research University, Belgorod, Russia

Issue:  Volume 49, №27

Rubric:  Physics

Annotation:  The principal possibility of forming in a layer of a homeotropically oriented nematic diffraction grating by an electric field of a group of closely spaced p-n junctions is experimentally demonstrated when the latter is excited by an alternating voltage, and the appearance of a grating is of a threshold nature. The diffractive elements of the grating are the regions of reorientation of the nematic, two for each p-n junction separated by a area of the homeotropic orientation that appear under the action of the electric field penetrating into the layer of the liquid crystal from the space-charge region of the p-n junction. It is established that the constant bias, the frequency of the alternating voltage, the intensity level of the illumination can be used as parameters for controlling the nematic reorientation threshold by an electric field in the vicinity of the p-n junction. Varying the width of the space charge region, and, consequently, penetrating into the liquid crystal layer of an electric field, by the level of external illumination, can be placed in the principle of functioning of an optically addressed light modulator. The observed change (increase) in the grating period with increasing voltage is associated with a change in the number of diffracting elements due to their overlapping, as well as depletion and possible inversion of the conductivity type of the pockets in a substrate of a different type of conductivity

Keywords:  diffraction grating, liquid crystals, p-n junction

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