[Show abstract][Hide abstract] 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 0.6μm 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 (≈750μm) 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.
[Show abstract][Hide abstract] ABSTRACT: We ascertain by measuring the surface topography of a cleaved sample in which damage lines have been written in volume by scanning with a femtosecond laser, that matter shearing occur along the laser track with alternating sign (scissor or chiral effect). We note that the shearing in the head of the laser tracks change its sign with the change in scanning direction (pen effect or non reciprocal writing). We also show that nanostructures in the head are nano-shearing, with all the same sign whatever the direction of writing may be. We suggest that symmetries revealed by the shearing mimic the laser induced electron plasma density structures and inform on their unusual symmetries induced by the laser beam structures.
[Show abstract][Hide abstract] ABSTRACT: We describe a high temperature route elaboration process of metamaterials: monocrystals of Cu(Ge,Si)O3 with SiO2–GeO2 glass fibers embedded in it. It is a novel type of two-phase material obtained starting from a mixture of oxides carried to fusion in a floating zone furnace and solidified in a preferred direction. The synthesized material exhibits nearly periodic fiber structures for a range of parameter set. This method opens up the possibility to produce photonic crystals at low cost and in great quantities.
No preview · Article · Apr 2008 · Solid State Sciences
[Show abstract][Hide abstract] ABSTRACT: We show, measuring the surface topography of a sample in which damage lines have been written by scanning a femtosecond laser, that nano structures in the focus (called in the literature: nanogratings, nanoplans, nanocrakcs) are nano-shearings, with all the same sign. We call this the scissor effect that gives rise to chiral structures. By separating the shearings dependent on the writing direction from the one not dependent, we show, first, that the shearings in the tail of the laser tracks are only defined by the laser scan line orientation not by its direction, and second, that the shearings dependent on the direction of laser scanning and changing of sign with the scanning direction are perpendicular to the laser polarization We call this the pen effect.