Optical fiber is as fast as ... speed of light

Researchers at the University of Southampton, UK have just created a new type of fiber optic cable that can transmit data at a rate of 99.7% of the speed of light.

Through testing, this type of fiber optic cable has a transmission rate of 73.7Tb / s (terabit / s) - equivalent to every 10TB of transmission (1 TB = 1024 GB = 1,048,576 MB), 1000 times faster than with the existing advanced 40Gb fiber optic cable and much lower latency (latency).

The speed of light in a vacuum is 299,792,458m / s but will be much slower in other environments. In conventional fiber optic cables (silica glass fiber optic cable), the speed of light is 31% slower. In fact, light moves faster through air instead of glass. So Francesco Poletti and the team at the University of Southampton invented an empty optical cable with a "gut" of air.

This is not the first time researchers have been thinking of making an empty fiber optic cable, but the biggest obstacle is that if the cable is bent, light cannot be transmitted. For today's popular fiber cable, glass or plastic materials have a refractive index that causes light to reflect around the inside of the cable, thereby allowing it to travel further. However, if a part of glass / plastic is removed and the light is out of the protective shell, the signal will decline almost immediately. In addition, the glass-air surface inside each cable also causes many problems, such as signal interference and limiting the total optical bandwidth of the transmission line.

Researchers at Southampton have overcome these problems by improving the hollow core design, using an ultra-thin photonic-bandgap wrap. This new design allows the light loss ratio to be reduced to 3.5dB / km, 160nm wide bandwidth and low latency. Therefore, data is transmitted at 31% faster speed. To achieve the transmission rate of 73.7Tb / s, the researchers used Wavelength Division Multiplexing to simultaneously transmit 37 40Gb signals with an empty cable. As of now, this is one of the fastest transmission rates achieved in the laboratory.

For practical applications, the rate of light loss of 3.5dB / km is a significant number, but the "hollow" type of fiber optic cable above will not replace the current fiberglass fiber optic system. . For short distances, such as between data centers and super-charged interconnection networks, this type of fiber optic cable will provide a significant improvement in speed as well as minimize the delay.