Float zone method for forming structured composites containing equidistant (Ge,Si)O2 fibers in a matrix of single crystal Cu(GeSi)O3

Abstract

Monocrystals of Cu(Ge,Si)O₃ with self-organized SiO₂–GeO₂ vitreous fibers running along the growth axis of the crystal, is a promising class of composites. This new material is achieved by floating zone technique using a ceramics with a composition located in a two-phase domain of the stability diagram of Cu(Ge,Si)O₃. We report our results on the relation between the various crystal growth parameters and the periodicity and the size of the fibers. We reached 1.2 and 0.6 μm respectively, and the refractive index contrast is around 0.35. These figures open the door towards telecom applications. These ones are important information for the realization of this composite from these oxides. After observation of the transverse section of this material, we report long fibers (≈750 μm) not published so far as second phase structure. After chemical analyses, we showed that physico-chemical conditions are met for the appearance of Turing like structures, explaining in such a way that the composite self-organizes during the solidification and turns into an ordered structure that can be useful as metamaterials or photonic crystal. This can help for suggesting other oxide systems and to define a general method for self-organization starting in the neighbourhood of an eutectic mixture.