Download Ongoing Research Works

Ongoing Research Works
The sol-gel process is one of the most promising of the developing techniques for
synthesizing new optical materials. The great interest and advantage of this technique is that it
uses lower temperatures than conventional methods, which is particularly important for the
encapsulation of many chemical compounds namely, organic dyes, semiconductor nanoparticles
(Quantum Dots) and biological materials.
I.
Solid state dye lasers by sol gel techniques
Incorporation of dyes into glasses prepared by the sol-gel process enables the design of new
types of stable solid lasers tunable in the visible range. The potential advantages of the sol-gel
method for preparing optical materials include obtaining new chemical compositions, better purity
and more convenient processing conditions. Therefore, the laser performance of each material can
attempt to characterize in a way which allow direct comparisons of their efficiency and
photostability. Photostability is a feature of prime importance in selecting a laser dye as it
ultimately governs the longevity of laser operation. However, some improvement was recently
found in the fluorescence intensities, laser efficiencies and photostabilty by co-doping dyes
(mixture of two dyes). Still, for applications that require high powers, at either cw or pulsed highrepetition-rate operation, the problem of heat dissipation is a serious impediment for their
utilization.
II.
Fluorescent dye doped nanoparticles for bioanalysis by sol gel process
Luminescent nanoparticles including silicon nanoparticles (QD), nano dye silica particles are
currently used in many areas of bioanalysis. Silica based nanoparticles show less aggregation and
little dye leakage. Using appropriate synthetic conditions, a large number of dye molecules can be
incorporated inside a single silica particle which produces a highly amplified optically signal
compared with a single dye molecule. Moreover, as the dye is trapped inside the silica matrix,
which provides an effective barrier keeping the dye from the surrounding environment, both
photobleaching and photodegration phenomenon that often affect conventional dyes can be
minimized. Therefore, excellent photostability makes these nanoparticles suitable for applications
where high intensity or prolong excitations are required.
III.
Luminescent Si nanoparticles (QD) by sol gel techniques
Nanoparticles of metals, semiconductors such as Si nanoparticles in transparent media have
especially in sol-gel glasses, received a great attention due to their promising applications in nonlinear optics and optical switches. The main technological problem to be solved prior to making
these composites of real interest for application in the field of opto-electronics, photonic and
biosensing devices is the necessity to further reduce both the average size and the size distribution
width of the nanoparticles in order to tailor the wavelength emission and bandwidth
.Nanocrystalline silicon (nc-Si) can be embedded in silica matrix fabricated using sol-gel methods.
Because stabilization of Si nanoparticles photoluminescence properties in solid sol gel media is
great interest for optical devices. Therefore, optical, mechanical, electrical and photo stability
properties of samples, with different concentration and sizes distribution of Si-nanoparticles, are
still important in order to have the optimum conditions for special applications.