A new concept in optical fibre technology

Researchers at the Australian Photonics Cooperative Research Centre have fabricated the first microstructured polymer optical fibre.

Polymer-based microstructured optical fibres (POF) offer key advantages over both conventional polymer optical fibres and glass microstructured fibres.

Their low-cost, manufacturability, and chemical flexibility provide great potential for applications in data communication networks and for the development of a range of new polymer-based fibre-optic components.

Despite these achievements, however, POF has not yet achieved widespread deployment in either datacom applications or telecommunications networks.

That’s because conventional POF has a number of disadvantages. Traditional large-core multi-mode step-index POF suffers from very large modal dispersion. The fabrication of single-mode POF, ideal for telecommunication purposes, has proved to be challenging, and the associated small mode area limits the applications. The technology used to manufacture the current state-of-the-art POF, the large mode-area graded-index multi-mode POF (GI POF), relies on a complex polymerization process to obtain a particular graded refractive-index profile across the diameter of the fibre.

A further reduction of the number of useful polymers is related to the absorption losses in the material, which has led to the use of fluorinated polymers. However, even in the case of these fully fluorinated materials, the use of conventional POF has been limited to a few hundred metres.

Now, however, researchers at the Australian Photonics Cooperative Research Centre at the University of Sydney have fabricated the first microstructured polymer optical fibre (MPOF).

This new type of POF, they claim, is likely to be of great importance, because all of the disadvantages of conventional POF have been potentially addressed.

The light guiding mechanism in MPOF is fundamentally different from that of a conventional POF. It arises from a pattern of microscopic air channels that run along the length of the fibre, rather than from variations in the refractive index of the fibre material.

The application of this guiding mechanism to POF offers a range of unique new properties and benefits. These include the possibility to combine single-mode behaviour with large mode areas, which is the ideal combination for easy-to-install transmission fibre. In addition, recently developed photonic band gap fibres offer the promise of guidance in air rather than in the fibre material, allowing the problem of absorptive losses of polymers to be addressed.

‘Polymer Microstructured Optical Fibres can be made from a single polymer material system, which means that all the cost advantages to be gained from highly economically efficient manufacturing can be passed on to customers’, said Dr. Ian Maxwell, CEO of Redfern Polymer Optics, whose fibre product range is based upon research carried out at the Australian Photonics Centre.

‘Optics Express’, the Optical Society of America’s newsletter featured an in depth article (epubs.osa.org/opticsexpress) announcing the new technology on September 24th.