Speciality fibres form next generation networks

Dr Chris Emslie, Managing Director of speciality fibre expert Fibercore Ltd, explains that the existing copper cable infrastructure may prove inadequate for near-term telecomms demand.

FTTH (fibre-to-the-home), FTTB (fibre-to-the-business), FTTC (fibre-to-the-curb) - whatever the combination for the next generation of metropolitan networks, optical fibre will undoubtedly play a significant part of the infrastructure.

Driven by an ever-increasing consumer demand for bandwidth, to support the latest applications that require high-speed data access, a return to prosperity in telecomms is now dependent on the development of a state-of-the-art optical infrastructure in metropolitan areas, which will cater for the demands of both business and domestic customers.

Dr Chris Emslie, Managing Director of speciality fibre expert Fibercore, explains that the existing copper cable infrastructure may prove inadequate for near term demand.

He explains why, whatever the final make-up of the metropolitan network jigsaw, recent developments in speciality optical fibre provide cost effective and future proof solutions to the challenges of delivering increased bandwidth.

Having backed the fibre-to-the-home horse in the steeplechase that is the current telecommunications industry, recent research shows that the balance of power in the metro network, or FTTx, landscape is shifting.

A recent report by US analyst Render Vandersplice quotes that demand in the fibre-to-the-business market is overtaking fibre-to-the-home and will continue to grow by a further 300% (from Jan 2002 levels) by the end of 2003.

The same source also forecasts that more than 1 million homes in the USA alone will have fibre connections by the end of the year.

Projected growth of this size in the FTTB market may be seen by some as yet another complication given the current maelstrom in the telecomms industry.

In truth, it means that telecomms operators have the opportunity to increase revenues in the short term in two markets if only they can modify their network architectures.

This shift in power from domestic to business users is not limited to the USA.

Initiatives like Broadband Britain and the e-Japan initiative have focused on the FTTH market, ensuring that broadband connectivity is available to the business community and in turn, helping to ensure that a recovery in telecomms is not restricted to the uptake of new consumer services.

Indeed, the e-Japan programme has, I believe, been responsible in part for the increase in demand we have experienced for erbium-doped fibres from Chinese amplifiers and 'amplets' manufacturers.

In the UK, however, the number of businesses with access to broadband networks remains below 1 in 10, illustrating the huge potential for growth in the FTTB market around the world.

Many operators have banked on the latest generation of interactive digital television, Internet and gaming services in the consumer market forming the basis for any resurgence in telecomms.

It is likely, however, that unless they are proactive in creating consumer demand, this resurgence is unlikely to occur until the current 'thumb generation' matures.

Why? Well given the limited disposable incomes of the current consumers of the Internet, mobile telephones, CATV and gaming, the focus will remain for basic services and bargain basement prices.

The main driver in the intervening years is very definitely the business user, which is demanding an increasingly state-of-the-art telecomms infrastructure in order to enable businesses to keep their fingers on the pulse of an economy.

Economic prosperity is increasingly reliant on real time information and communications and the main barrier for operators fulfilling this latest increase in demand is investment in metro networks - or a lack of it.

Why is this? Well, for telecommunications infrastructure manufacturers and systems designers an increase in demand means developing a new metropolitan blue print with a greater number of higher performing components in the same amount of real estate, which delivers increased capacity for both commercial and domestic consumers.

There has already been an increase in the development of passive optical networks (PON) in key metropolitan markets, but the widespread installation of fibre throughout every major US town and city is costly and time consuming.

Both of these commodities are currently in very short supply for many telecommunications companies.

There are, however, two potential solutions that will enable operators to offer increased bandwidth with dramatically reduced speeds to market: the development of hybrid fibre coax (HFC) networks, and the creation of state-of-the-art free space optical communication infrastructures.

This will enable operators to increase short-term revenues by enabling the delivery of a greater number of better quality services.

Both these solutions can benefit from recent advances in speciality optical fibres.

The first is the reduction in diameter of erbium-doped fibres for amplifiers or 'amplets'.

Contrary to the myth perpetrated by many startups in the speciality fibre marketplace that reduced diameter fibres are a new innovation, nothing could be further from the truth.

Fibercore developed the first 80-micron fibre for the gyro market more than two decades ago and first promoted its use in telecomms in 1995.

We now ship more than 300km of reduced diameter fibre every month.

This volume production translates to expertise and tangible quality and consistency - both of which are essential to the rejuvenation of telecomms.

Using 80-micron fibres dramatically reduces the bend stress, and therefore increases life expectancies of the fibre (overcoming a major concern among systems developers and network architects).

Given that an average amplifier contains anywhere between 5 and 20m of fibre to enable it to be spliced and coupled, reducing the fibre diameter allows manufacturers to decrease the form factor of component packaging.

This is despite the requisite excess of fibre that is required in component production to enable the simplification of the production process.

To meet these requirements, Metrogain M12 (80), Fibercore's latest erbium-doped amplifier fibre, has been honed specifically to the requirements of FTTX networks.

These reduced diameter erbium doped fibres are also supported by a range of fully compatible component fibres, optimised for pump pig tailing and WDM fabrication.

In addition to reducing the form factor, we have been able to increase pump absorption to twice the normal level (and up to four times the absorption of some fibres).

This enables component manufacturers to reduce gain section lengths of metro EDFAs to about 4m - increasing the amount of hardware (add-drop multiplexers, splitters and amplifiers) they can fit in to the same amount of real estate.

This will help reduce the cost of rolling out performance improvements across an entire metropolitan infrastructure.

The second advance in speciality optical fibre is the development of new and increasingly powerful cladding pump fibres, such as Fibercore's pioneering all-silica CP range.

We have pioneered the market's first, and still the only, all-silica cladding pump fibre, which has a unique quasi-polygonal architecture that significantly increases the amount of pump energy that can be channelled into the core.

This has dramatically increased the power output of pump lasers and made the dream of multi-watt lasers a reality.

In addition, the all-silica construction of our CP range has delivered notable improvements in handling and device production and has a significantly higher optical damage threshold than traditional silica/polymer cladding pump fibres.

These fibres so can be spliced and cleaved in the same way as any conventional fibre also vastly simplifying general handling and component fabrication.

The upshot of these developments is increased reliability, greater transmission distances and lower cost of free space optical communications.

In the short term, where both reducing costs and increasing revenues are key priorities for operators, free space in metropolitan networks provides an attractive proposition for the industry.

The flexibility, speed of deployment and increased bandwidth that line of sight optical communications offer will enable a dramatic increase in high speed broadband connectivity and help to increase ARPU (average revenue per user) easing cash flow.

The proof of just how far free space has come over the last decade is the rapid deployment of reliable free space communications on Wall Street in the immediate aftermath of the 11th September 2001.

Both HFC networks provide a way of delivering video, voice telephony, data, and other interactive services over coaxial and fibre optic cables.

In the metro marketplace, the development of HFC networks using speciality fibre addresses many of the major requirements of the telecomms market, both throughout 2003 and beyond.

A reduced form factor fibre will not remove the cost and time required to fibre or refibre a network, but it does provide operators with a way of modifying networks in line with current and future demand by increasing component density within existing real estate.

Broadband line of sight optical networks could also be used to complement existing infrastructure or as a short term, low cost solution while embedded networks are upgraded or as part of new state-of-the-art network architectures using free space optics.

There is no doubt that speciality optical fibre will play an important part in fibre lasers used for transmitting information such as television signals, Internet packets, and streaming media from up-link stations to distribution centres, through a Sonet ring.

In addition, reduced form factor speciality fibre with a diameter of 80um could also be used in fibre amplifiers as part of DWDM hardware at the fibre node, to increase both the bandwidth of existing coaxial cable and the number of subscribers serviced by each node.

Indeed, Fibercore's ongoing development programme has yielded excellent results at 50um or smaller.

The barrier to widespread use of reduced form factor speciality fibre in telecomms components has until recently been that 80um was seen as a weird and wonderful photonic development for the aeronautics, defence and sensing markets.

Historically, telecomms has always stuck with what it knew.

That view has changed over the last 18 months as telecomms component manufacturers have begun to understand the true value of reduced form factor fibres for telecomms applications.

Using the fibre gyro market as an example, the need to tightly coil many metres of fibre would place a huge intrinsic stress on a standard 125-micron fibre causing it to fail very quickly (and making them unsuitable for commercial airliners).

At Fibercore we are starting to see a small, but steady increase in demand for our reduced diameter 80-micron speciality fibre from components and amplifier manufacturers.

As a result of our ongoing fibre research and development programme over the last three decades, working for a host of diverse industries including sensing, aviation, defence and telecommunications, our reduced diameter telecomms fibres have proven track records.

Our 80-micron fibres have all passed Telcordia compliance tests and can demonstrate life spans of between 20 and 30 years in typical small form telecom component deployment.

For telecomms companies needing a broadband network to serve the varied requirements of a modern metropolitan market, developments in speciality fibre provide solutions to almost every challenge.

Free space optics (FSO) provides a cutting edge solution where refibring is not logistically or financial viable and now advances in fibre laser technology now make high-bitrate communications possible.

Long seen as a futuristic 'vision' of optical communications, FSO was thrust under the spotlight in the immediate wake of the 11th September 2001 World Trade Centre disaster when it enabled communications to be re-established on Wall Street within hours of the attack.

Early experiments with through the air optical communications in the late 1960's used green lasers and proved unreliable in precipitous climates and green lasers were fundamentally not eye safe.

With our pioneering fibres it has been possible to develop free space optical technology which operates in the infra-red to deliver eye-safe, high performance line of site optical communications.

The most recent model for FSO has been using transmitters and receivers atop skyscrapers beaming infra-red laser beams around densely populated metropolitan areas to create private commercial virtual local area networks (VLAN's) and WAN's (wide area networks) between commercial properties.

Given the current growth in business demand for broadband networks in metropolitan areas, there may be another solution to broadband free space optical community.

By combining the developments in HFC networks and advances in free space technologies operators could provide businesses with cost effective high performance broadband access using FTTC access points and vertical FSO connectivity - effectively reducing the requirement for fibre to be laid to every individual property.

Regardless of the type of consumer, the long-term solution to developing the metropolitan networks of the future seems clear.

Rather than looking to the future with a sense of resignation and helplessness as the number of hurdles continues to increase, the telecommunications industry must use the existing technological developments to enable them to address the current bandwidth requirements.

For the consumer that will provide greater access to broadband networks and improved services - for telecomms companies, it means survival to fight another day.

By using the latest high performance and reduced diameter speciality optical fibres to get the most out of existing infrastructure, the industry will buy itself the time to innovate a revolutionary blue print for the next generation of metropolitan networks which quenches the growing thirst for bandwidth in both the domestic and commercial marketplaces.

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