The well-established catalyst-free sonogel route was successfully implemented
to fabricate highly pure, optically active, solid state polymeric azo-
dye/SiO2-based hybrid composites. Bulk samples exhibit controllable geometrical shapes and
monolithic structure with variable dopant concentrations. Since the implemented azo-dye
chromophores exhibit a push–pull structure, hybrid film samples were spin-coated on
ITO-covered glass substrates; molecular alignment was then performed via electrical poling
in order to explore the quadratic nonlinear optical performance of this kind of composite.
Comprehensive morphological, spectroscopic and optical characterization of the samples
were performed with several experimental techniques: atomic force microscopy,
x-ray diffraction and infrared, Raman, photoluminescent and ultraviolet–visible
spectroscopies. The linear refractive indices of both bulk and thin film samples were
measured according to the Brewster angle technique and a numerical analysis of the
transmission spectral data, respectively. Regardless of the low glass transition
temperatures of the studied polymers, some hybrid film samples were able to display
stable nonlinear optical activity such as second harmonic generation. Results
show that the chromophores were satisfactorily embedded into the highly pure
SiO2
sonogel network without significant guest–host molecular interactions, thus preserving their
optical properties and producing sol–gel hybrid glasses suitable for optical applications.
In the present work, oxalic amorphous porous anodic alumina membranes with highly ordered porous arrays and average nanometric porous dimensions of 70 nm in diameter and 17 microns in depth (nanotubes) were prepared and successfully used as host matrix for fluorinated bent-core liquid crystals. Atomic force microscopy studies were performed on the organic-inorganic hybrid samples in order to explore surface morphology and optimal insertion of these liquid crystalline (LC)-compounds into this environment. The quadratic nonlinear optical (NLO) and spectroscopic properties of the implemented mesogen with the nanotube-like confinement were systematically studied in order to evaluate its optical performance. Bent core molecules have shown interesting optical properties which have not yet been intensively investigated in solid-state hybrid structures. Hence, the obtained hybrid composites represent a promising field of investigation in the route to functional bent-core based materials, where different bent-core mesomorphic structures can be obtained and are of interest for new and improved applications in nanotechnology.
In the present work, oxalic amorphous porous anodic alumina membranes (AAM) with highly ordered porous arrays and average nanometric porous dimensions of 70 nm in diameter and 37 microns in depth (nanotubes) were prepared and successfully used as hosting matrix for C 60 and C 70 fullerene compounds. Atomic force microscopy (AFM) studies were performed on the hybrid samples in order to explore surface morphology and optimal insertion of these molecular systems into the AAM environment. The cubic nonlinear optical (NLO) properties, such as nonlinear refraction and absorption of the hybrid samples were studied via the Z-Scan technique in order to evaluate their NLO-performance. Hybrid AAM with fullerene compounds have shown outstanding NLO-activity with positive NLO-refractive coefficients.
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