Tunable optical and nonlinear optical response of smectic glasses based on cobalt alkanoates

Abstract

The nonlinear optical response of anisotropic smectic glasses based on cobalt alkanoates has been studied using dynamic holography. Laser-dynamic gratings induced by the action of nanosecond laser pulses were observed and analysed for such materials. It was found that the cubic optical nonlinearity of all the anisotropic glasses studied had an electronic origin in the nanosecond range, caused by nonlinear polarisation of the cobalt alkanoate complexes. Fundamental optical (refractive index and absorption coefficient) and nonlinear optical (nonlinear susceptibility and polarisability) parameters of mesomorphic glasses based on cobalt alkanoates could be tuned by varying the length of the alkanoate anion chain, thereby determining the interlayer smectic distance.

Nonlinear Optical Response of Smectic Glasses Based on Cobalt Alkanoates

“…The following types of chemical compounds were used in the studies of nonlinear-optical properties: As was shown in our previous works, all studied materials form the liquid crystal state (Smectic A) [11,12] under melting. It should be noted that the abovementioned liquid crystalline materials can be easy vitrified under cooling.…”

“…It should be noted that the abovementioned liquid crystalline materials can be easy vitrified under cooling. Such a vitrified state can be considered as the "frozen" liquid crystal state and is stable for a long time at room temperature (in fact, samples are still in the glass state even after 1 year after their preparation) [12]. For this reason, the studied glasses are anisotropic and can be called "mesomorphic glasses" in contrast to the well-known isotropic glasses.…”

“…For this reason, the studied glasses are anisotropic and can be called "mesomorphic glasses" in contrast to the well-known isotropic glasses. temperature of the phase transition "crystal-liquid crystal") using both the capillary technique [11,12] and the crushing method. After the melting to the liquid crystal state, all samples were cooled to achieve the glass state.…”

Phase Diagrams of Mesogenic Binary Systems of Cobalt(II) and Univalent Metal Octanoates

“…Mesogenic sodium, potassium, and thallium(I) octanoates have unlimited solubility in cobalt(II) octanoate mesophase in accordance with the ionic mesogenicity rule, and nonmesogenic lithium octanoate is only partly soluble in it. When studying the phase behaviour of binary systems based on cobalt(II) octanoate with alkali metal and thallium(I) octanoates, formation of optically anisotropic mesomorphic glasses has been established; these glasses absorb light in the visible wavelength range [18], making it possible to use them as universal liquid crystalline matrices in the creation of novel photorefractive and nonlinear optical liquid crystalline materials.…”

Electric Properties of Ionic Thermotropic Liquid Crystals

“…1). The cells were filled with studied liquid crystalline materials at a hot plate at temperature > C−LC ( C−LC is the temperature of the "crystal-liquid crystal" phase transition), by using the capillary technique [17,18]. To prevent the "absorption" of water in the sample, the cell edges were sealed with glue.…”