Nanooptics and Nanophotonics 

Surface-confined optically controlled liquid crystal elements
Bugaychuk S.1, Kredentser S.1, Kurioz Yu.1, Viduta L.1, Styopkin V.1, Gridyakina A.2, Bordyuh H.2
1 Department of Physics of Crystals, Institute of Physics of the NAS of Ukraine. Prospect Nauki, 46, Kyiv-03028, Ukraine. 
E-mail: bugaich@iop.kiev.ua
2 Department of General and Applied Physics, National Aviation University, Liubomyra Huzara ave. 1, 03058 Kyiv, Ukraine.

Nowadays, dynamic holography has evolved into powerful techniques for a variety of applications, including optical information technologies, artificial intelligence, wavefront conjugation. The main electrically controlled optical elements become spatial light modulators (SLM), which are based on liquid crystal cells. Nematic LCs (NLCs) are very effective and at the same time cheap materials for controlling the transmission of optical beams. But they have one essential drawback, namely a slow response time (typically 50-100 ms) to the action of an electric field, which significantly limits their use in optical information technologies. The current trend to overcome this problem is to create confined nanoscale regions inside the NLC cell. 
Our efforts are directed to studying the surface-induced photorefractive effect (SIPE) in NLC cells, when the confined effect is achieved at the interface of a thin NLC layer on a special type of substrate surface [1]. The SIPE mechanism allows the response time of NLC cells to be reduced more than one order of magnitude. Another advantage of holographic methods is the ability to create optically controlled NLC cells. In this case, the control parameters can be: the intensity of laser beams, their polarization, frequency of laser pulses, and others. We consider two types of surfaces at the inorganic/organic interface contained in the composite cells: (i) a gold nano-island film deposited on a ITO layer covered a glass substrate; (ii) chalcogenide glass substrates. The results of modeling of SPIE mechanism in NLC cells, which includes the formation of a controllable space charge field at the inorganic/organic interface containing a nanoscale NLC layer are presented as well. Such composite cells can be used in manufacturing ultrafast SLM and other electro-optical LC-base devices with fast response time.

1.	Bugaychuk S, Viduta L., Gridyakina A., Bordyuh H., Styopkin V., L. Tarakhan, V. Nechytaylo, Faster nonlinear optical response in liquid crystal cells containing gold nano-island films // Appl.Nanosci. -2020.-10:-P. 4965.