What’s New With Fiber Optics?

The companies that operate the long-haul fiber networks say that we are in danger of running out of bandwidth capacity on the major fiber routes between major Internet pops. The capacity of the current fiber optics along with the number of pairs of fiber between pops creates a finite maximum amount of bandwidth that can be transmitted – and with worldwide bandwidth usage still growing exponentially it’s not hard to foresee exhausting the capacity on key routes. We can always build new fibers, but it’s hard to build enough fibers anywhere to keep up with exponential growth.

But as expected, there are a number of new developments coming out of research that will probably let us stay ahead of the bandwidth curve. There is always a time delay between lab and manufacturer, but it’s good to know that there are breakthroughs on the way.

Frequency Combs. Engineers at San Diego’s Qualcomm Institute have developed a technique that could significantly improve the throughput on long-haul fiber routes. Today’s fiber technology works by transmitting multiple separate ‘colors’ of light operating simultaneously at different frequencies. But as more frequencies are jammed into a single fiber there is an increase in crosstalk, or interference between frequencies. This interference today limits the ‘power’ of the signal transmitted through a single fiber.

The Qualcomm engineers have developed a technique they are calling frequency combs. This technique grooms the outgoing light signal of each frequency so that the downstream interference is not random and can be predicted. And that is allowing them to then use an algorithm at the other end to detangle and interpret the scrambled data.

In a test this technique has created remarkable improvements. The engineers were able to increase the transmit power of the signal by 20-fold and then transmit the signal for 7,400 miles without the need for an optical regenerator. There is still work to be done, but this technique holds out great promise to be able to boost bandwidth on existing fibers.

Corkscrew Lasers. A team of scientists at the University of Buffalo’s School of Engineering and Applied Science have developed a new technique that can also increase the amount of bandwidth in a given fiber. They are taking advantage of a phenomenon that has been known for decades that takes advantage of the angular momentum to create what is called an optical vortex. This essentially creates the equivalent of a funnel cloud out of the light beam, which allows piling on more data onto a laser data stream.

For years it was always thought that this phenomenon would be impossible to control. But the team has been able to focus the vortex to a small enough point that can interface with existing computer components. The upside is that the vortex can transmit about ten times more data than a conventional linear laser beam, providing a boost of a full magnitude in laser power.

Air Fiber. A team at the University of Maryland has been able to create fiber-like data transmission feeds without using fiber. They are using a short powerful burst of four focused lasers to create a narrow beam they are calling a filament. The hot air expands around this filament creating a tube of low density air. This filament has a lower refractive index than the air around it and creates an effective mirrored tube – that can act just like a fiber optic filament.

The team has demonstrated in the lab that shooting four lasers to create the filament, followed by a short laser burst down the center of the filament, creates a temporary data pipe. The filament lasts only one-trillionth of a second, but the ensuing data beam lasts for several milliseconds – enough time to create a 2-way transmission path. The system would be used to create repeated filaments and this create a fiber path through the air.

For now the team has been able to make this work in the lab over a distance of a meter. Their next step is to move this to 50 meters. They think this theoretically could be used to transmit for long distances and could be used to create data paths in places where it’s too expensive to build fiber, and perhaps to transmit to objects in space.