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Abstract. The photonic crystal is the material which structure is characterized by periodic distribution of refraction index in the spatial directions, which have the photonic band gaps in a spectrum of own electromagnetic states. There are numerous approaches of the creation of photonic crystals. In the present the optimal conditions of synthesis of photonic crystals based on silicon dioxide as well as the inverse photonic crystals based on vanadium dioxide are investigated. It is known that the synthesis process is influenced by many different factors. We have studied the dependence of the particle size on the concentration of reagents, as well as on the duration of the reaction. These studies are important for the production of samples of photonic crystals with a definite structure. IntroductionOne of the most important areas of modern physics is the study of periodic optical nanostructures, known as photonic crystals (PC) in which the dielectric constant varies periodically in space with period allowing Bragg diffraction of light. It is known that crystals of all types can disperse some radiation, provided that the period of the crystal lattice is of the same order as the wavelength of the radiation. Similarly, photonic crystals do not transmit the light with a wavelength comparable to the period of the photonic crystal structure, at the same time PCs are transparent to a wide range of electromagnetic radiation spectrum. These spectral bands are called "photonic band gap" (PBG) [1]. The works on photonic crystals are motivated by a number of promising applications, such as high-performance light emitting diodes, lowthreshold lasers, optical waveguides with sharp bends and optical microchips. Nowadays there are numerous approaches to the creation of PC by using the lithography [2], interferential holography [3] and self-assembly of colloidal particles [4]. One of the first materials that have been considered as photonic crystals were synthetic opals, consisting of close-packed spherical particles of silica. Self-assembly techniques are very promising, since they are quite simple in terms of hardware design and have no fundamental restrictions both on the sample size and the number of photonic crystals produced in one cycle of synthesis. However, the synthesis process is influenced by the factors like setting of the concentration ratio of the reactants, reaction temperature, sequence of blending and more. So our purpose is to investigate the effect of concentration ratio of reactant and duration of the reaction on the particle size, making possible creation of PC with predetermined characteristics. Our results are relevant for the experimental verification of the effect predicted by the authors in [5].

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