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The photonics group initiates a new research activity in the Centre d'Electronique et de Micro-Opto-Electronique de Montpellier, laboratory of CNRS and of the 'Universite des Sciences Montpellier II
The group gathers competences in several domains : - sol-gel synthesis, fabrication of waveguides and gratings by sol-gel process, modelling and design of integrated optics devices, optical characterization. The diversity and the complementary of these competences come from the variety of the people involved :
- Institut d'Electronique du Sud
A simple technique, initiated in Montreal (Groupe Photonique, Ecole Polytechnique, S.I. Najafi and M.P. Andrews), based on a deposited layer of UV photosensitive organic-inorganic sol-gel silica glass onto a substrate : the waveguides are then drawn in this layer through a predefined photomask.
The sol-gel we have elaborated is a new photoreactive organo silico
zirconate compound. The material combines the
advantages of both organic and mineral materials for optical components.The layer is deposited by dip coating. The slight increase
in the refractive index, necessary to guide the light is due to a photopolymerization
of the double bond of the organic compounds, after a local exposure to
ultraviolet light. One of the important aspect of this process is that is
performed at room temperature, this allows a direct coupling of our all-optical
devices with opto- electronic components, on the same chip.
Look at the real pictures of light coming out of a home-made WDM,
depending on the wavelength:
Presently, we are able to make layers thick enough, it has been for a long time an obstacle to use sol-gel processed layers in integrated optics. We have optimised the sol-gel layers in thickness (7-9 µm) and in refractive index (1.48) to obtain an optimal coupling (low losses) with single mode optical fibers used in communications at 1.55 µm. Our waveguides are buried under a protective coating to improve propagation and scratch resistance, enabling an easy handling.
At that time, we have realized low loss codirectional couplers, beam splitters (1 x 4 and 1 x 8) and gratings with refractive index modulation. We actually make Wavelength Demultiplexers Multiplexers (WDM), see upper, and are examining the possibilities of realisation of optical amplifiers in rare earth doped sol-gel layers.
Also we have developped a modelling software to study and compare the various structures of waveguides, also we can simulate propagation in devices through the Beam Propagation Method.
Now we look for any help or financial support to furher develop finite products oriented to an industrial distribution. This technology appears to be very promising, among the all optics boom at the present turn of the millennium.
