Engi­neers have bro­ken the data rate record over fiber, reach­ing 319 ter­abits per sec­ond.

optical fiber

The world inter­net speed record was bro­ken when Japan­ese engi­neers demon­strat­ed data trans­fer rates of 319 ter­abits per sec­ond (Tb/s) over fiber optic cables. The record was set over a dis­tance of over 3,000 km using the exist­ing cable infra­struc­ture.

optical cable

It’s hard to even imag­ine how high this trans­fer rate is. It almost dou­bled the pre­vi­ous record of 178 TB/s set less than a year ago. NASA is get­ting by with “only” 400Gbps, and that’s absolute­ly space-sav­ing com­pared to the speeds cur­rent­ly avail­able to con­sumers. The fastest home inter­net con­nec­tions peak at 10Gbps in parts of Japan, New Zealand and the US, while the vast major­i­ty of sub­scribers in oth­er parts of the world are unlike­ly to exceed 1Gbps.

The break­through was achieved using the exist­ing fiber optic infra­struc­ture with the addi­tion of more advanced tech­nolo­gies. First, it used four “cores” — glass tubes inside the fibers through which data is trans­mit­ted — rather than a stan­dard sin­gle core. The sig­nals were split into mul­ti­ple wave­lengths trans­mit­ted simul­ta­ne­ous­ly using a wave­length divi­sion mul­ti­plex­ing (WDM) tech­nique. To trans­mit more data, a rarely used third “band” is added, and the dis­tance is increased thanks to opti­cal ampli­fi­ca­tion tech­nol­o­gy.

Dia­gram of the new NICT trans­mis­sion sys­tem:


The sys­tem starts with a comb laser that gen­er­ates 552 chan­nels at dif­fer­ent wave­lengths. This light then goes through dual polar­iza­tion mod­u­la­tion, delay­ing some wave­lengths to cre­ate dif­fer­ent sig­nal sequences. Each of these sig­nal sequences is then fed into one of the four strands of the opti­cal fiber.

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The data trav­els approx­i­mate­ly 70 km along the fiber before meet­ing opti­cal ampli­fiers to keep the sig­nal strong over long dis­tances. Here it goes through two new types of fiber ampli­fiers, one doped with erbium and the oth­er with thuli­um, before going through a com­mon process called Raman ampli­fi­ca­tion. The sig­nal sequences are then sent to the next seg­ment of the opti­cal fiber. Repeat­ing this process allowed the team to trans­mit data over an impres­sive dis­tance of 3,001 kilo­me­ters.

It is impor­tant to note that a four-core opti­cal fiber has exact­ly the same diam­e­ter as a stan­dard sin­gle-core fiber, tak­ing into account the pro­tec­tive sheath. This means that this tech­nol­o­gy should be rel­a­tive­ly easy to imple­ment into exist­ing fiber optic infra­struc­ture.

A paper describ­ing this achieve­ment was pre­sent­ed at the Inter­na­tion­al Fiber Optic Con­fer­ence last month.