Hollow Core Fibre & Its Potential In Long Haul Networks

Hollow core transmits light via a central air filled tube in the fibre optic strand versus solid ultra-pure silicon. The benefit is 50% less latency which brings it within 1% of light's maximum speed. High attenuation bedeviled this technology's earliest incarnations as light would bleed and escape through the cladding. A founder of Lumenosity, the preeminent hollow core manufacturer, stopped light bleeding using a reflective layer made of silver. Photonic bandgaps are also used for the same purpose.

The fibre offers several performance advantages over traditional solid core fibre:

1. Lower latency since light travels 50% faster via air.

2. Air generates less chromatic dispersion than glass. Chromatic dispersion involves the different frequencies making up a light pulse moving at different speeds. This causes a pulse meant to occupy one time slot to spread and occupy multiple time slots. The data is corrupted.

2. Less nonlinear distortions such as 4 wave mixing, stimulated Brillouin scattering, and self phase modulation. These problems arise when high power levels are used in lasers in order to handle greater distances or achieve higher bit rates.

3. Low attenuation because silicon absorbs and scatters light more than air.

Alas, this sexy new technology has drawbacks:

1. Hollow core requires more sophisticated and expensive manufacturing. The intricate cladding design plays a big role in raising costs.

2. The glass is more fragile due to the hollow spaces. The bending radius is small and general handling requires significant training.

Currently hollow core is a niche application. It is used by ultra-low latency traders who are fighting over micro-seconds and nanoseconds. EUNetworks is Europe's leader in low latency routes. It has deployed hollow core in metro markets such as London.

If you are an entrepreneur who wishes to be disruptive, deploy hollow core in the long haul. Most of us generally think of our bandwidth customers as more concerned with price than any other factor. But I have seen intense interest from my Tier 2 ISPs clients in routes that shave their round trip by one or two milliseconds. This reflects the fact that many of them are coming to Europe from Africa or Asia to peer in Europe. The high latency penalty of doing so makes them particularly interested in anything that leads to faster transmission and gives them an edge against their competitors. A long haul hollow core European network would be immensely popular. It might even command a premium over market pricing. The big challenge is the high cost of hollow core. Until manufacturing volumes increase, hollow core will remain very expensive. It currently lacks the production economies of scale to challenge mainstream solid core glass fibres. But volumes will increase and learning by doing will happen, so I look forward to building my ultra-latency network for ISPs in the 2030s. 😄