In this report we present the results of optical study of polymer polyethelene teraphtalate (PET) porous films filled with a nematic liquid crystal (NLC). Previously such composite system was proposed as perspective material for photonics applications [1,2]. The samples of porous films of thickness h = 20 μm, obtained by ion bombarding and further chemical etching, were characterized by normal orientation of pores relatively to the film’s plane with a narrow size distribution (the pore diameter’s range d = 0.1….5 μm). In present experiments the films were filled with a nematic mixture ZhK 440 (NIOPiK) and irradiated by UV (λ = 365 nm). It induced the time variations ΔIr (t) of the red light intensity (λ = 630 nm) passed through the film. It was found, that the value ΔIr (t) depended on the irradiation dose D = IUV *t ( IUV – the intensinty of UV irradiation). The slow (some hours) backward relaxation of Ir (t) to the initial value was observed after turning off UV irradiation. The observed effects were assigned to the changes of the effective refractive index of NLC imposed by UV induced cis-trans transitions of photo sensitive molecules of LC.
This work was supported by Ministry of Education and Science of Russian Federation, identification number- RFMEFI58316X0058.
1. Chopik A.P., Pasechnik S.V., Semerenko D.A., Shmeliova D.V., Dubtsov A.V., Srivastava A., Chigrinov V.G. Electro-optical effects in porous PET films filled with liquid crystal: new possibilities for fiber optics and THz applications // Optics Letters, Vol. 39, Issue 6, pp. 1453-1456 (2014).
2. Maksimochkin, G.I., Shmeliova, D.V., Pasechnik, S.V., Dubtsov, A.V., Semina, O.A., Kralj, S. Orientational fluctuations and phase transitions in 8CB confined by cylindrical pores of the PET film// Phase Transitions, 89 (7-8), pp. 846-855 (2016).
