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Graphic element Research > Growth > Research projects > Previous projects > New Products and Materials > Spotlight moves to optoelectronics
Graphic element Spotlight moves to optoelectronics
     
 
For innovation in today's rapidly changing society, faster is better, particularly when it comes to communications. Everyone wants to get on to the internet faster, to access and download lots of information from home, in their cars, and from their mobile phones. In the rush towards higher speeds and miniaturisation in telecommunications, fibre optics and its applications have rapidly taken centre stage. Now a Brite-Euram project has taken us yet another step closer to fast and efficient information transfer by producing extremely small components for use in optoelectronics, using sol-gel technology.
 

In recent years, a variety of sol-gel methods have been developed for the creation of ceramic and glass materials and coatings with tailored optical, electronic and mechanical properties. The term 'sol-gel' refers to the transition of liquid 'sol' (tetraethylorthosilicate or TEOS) into a solid 'gel' phase. Liquid TEOS is either applied, moulded or cast and then solidifies, forming a ceramic or glass substance in a wide variety of forms: ultra-fine or spherical shaped powders, thin film coatings, fibres, microporous inorganic membranes, monolithic elements or extremely porous aerogel materials. New materials for optoelectronic applications have also been developed using sol-gel casting.

Extremely fine components

This project set out to develop an improved low-viscosity sol gel which could be poured into extremely fine pattern moulds for producing high-precision glass optical elements for electronics and other applications. Such components would be particularly attractive in applications related to high-speed and broadband optical communications.
The partnership, which included industrial manufacturers and suppliers of sol-gel technologies and products, experts in optoelectronics and coating techniques, and academic bodies from Germany, Italy and the UK, was dedicated from the outset not only to getting the project successfully completed but to producing commercially marketable products.

Focusing on performance

The new sol material pours easily into a fine pattern mould. A condensation reaction then forms a solid gel network from the liquid. This hydrogel exhibits little or no adhesion to the mould surface and is stable enough to be removed from the mould. Further drying and high-temperature treatment is then used to harden and shrink the hydrogel cast so that it forms a smaller solid and ultra-pure glass form about half the size of the original and possessing excellent light transmission characteristics.
Materials for optical applications in the 780, 1 300 and 1 500-nanometre ranges were successfully fabricated using this technique, as were advanced extremely fine prototype optical gratings.
In addition, a new technology for making glass-amplifying waveguides was developed using commercially available glasses and glasses prepared by melting xerogel powders, with very homogeneous distribution of the rare earth ions in high concentration. And micro-optical elements such as tiny Fresnel lenses (shaped like the large cutaway lenses seen in many lighthouses) were produced using organic inorganic nanocomposites (Nanomers).
For fine circuit-like components requiring surface patterning, photolithographic and embossing techniques were used, including embossing with micropatterned moulds, laser patterning and photolithography.
Each of these major achievements in the project represents a significant advance in the state of the art, providing the technological basis for the fabrication of optical components at competitive costs for a variety of industrial applications.
Using the newly developed sol-gel moulding methodology, bare surfaces or surfaces loaded with microstructures can be duplicated for the same cost. It is therefore well suited even to the fabrication of very complex components, representing an important further step in miniaturisation. The new method is also fairly inexpensive and environmentally friendly compared to more conventional deposition methods.

Market place

Given the high performance and flexibility of sol-gel-derived materials, they will undoubtedly take their rightful place next to classic, traditional materials such as glass, silicon, lithium niobate, polymers and others in the optoelectronics market.
Solvent casting of sol-gel film is inexpensive compared to equivalent methods for porous silica film deposition (flame-hydrolysis deposition) on account of its use of cheaper and more readily available raw materials, the elimination of chlorine, and lower energy requirements. Estimates suggest a three-fold cost advantage compared to the same product made by flame-hydrolysis deposition.
The European market for lens arrays, waveguides and sol-gel-coated silica wafers has been estimated at more than 14 million euro per year. Operations are now being scaled up to enable the production of such elements for the rapidly expanding high-quality telecommunications, sensing and automotive markets.

Cordis RCN: 23147
More information (Cordis database)
   
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