Home Electronics 12,000 kilometers of fiber optic communication – without repeaters!

12,000 kilometers of fiber optic communication – without repeaters!

Taking things on from a different angle could lead to breakthrough discoveries in the other end – now scientists at University of California, San Diego, have found a way to eliminate the need for any repeaters and with only standard amplifiers when sending information through fiber optic cables. The new record is now an astonishing 12,000 kilometers of perfectly sent and decoded information.

Like the concert master of an orchestra works to tune all instruments to the same pitch before they all start to play, scientists have now figured out how to set the frequencies to a synchronized mode before sending them off into the fiber optic cable. And at arrival, the frequencies get “combed” and thereby unscrambled from all the expected distortions that occurred on their journey. The finding will have great impact on the internet delivery conditions all over the world.

Eduardo Temprana, first author of the paper, published in the journal Science, and also Ph.D. student in electrical engineering at UC San Diego, talks about their ground-breaking discovery: “After increasing the power of the optical signals we sent by 20 fold, we could still restore the original information when we used frequency combs at the outset.”

Previously it’s been necessary to add repeaters, electronic regenerators picking up and sending off frequencies to avoid the before mentioned distortions between the frequency channels, on regular distances of the cables, and this has been a both expensive and limiting approach.

Stojan Radic, professor in the Department of Electrical and Computer Engineering at UC San Diego and also senior author of the article, explains the distortion problem: “Crosstalk between communication channels within a fiber optic cable obeys fixed physical laws. It’s not random. We now have a better understanding of the physics of the crosstalk. In this study, we present a method for leveraging the crosstalk to move the power barrier for optical fiber.”

The test was conducted by synchronizing the frequencies of both 3 and 5 channels, but the system is fully capable of being upscaled to serve more than 32 channels in the same silica fiber optic cable, which is common today. These experiments on photonics were conducted at the Qualcomm Institute at the University of California, by researchers from the Photonics Systems Group, also led by Radic.

By taking command over the expected distortions that always happen when sending off several frequency channels in the same optic cable, and determining in advance how the distortions will occur, the scientists could also find a way to easily decipher the distortions in the other end. So far it’s not been possible to send information through fiber optic cable more than up to a certain distance, even when adding more power, because the phenomenon of “crosstalk” is unavoidable when channels share the same traveling space for longer distances.

With repeaters along the path, the cost increases and the optical networks lose some of the important transparency. The electronic regenerators are virtually small supercomputers and are currently needed in cables that carry between 80 and 200 channels, inducing heavy costs to any installation of fiber optic communication means. The new approach will eliminate this need, leading to cheaper, more efficient information transmission, as well as making the entire economy of the network infrastructure a target for new models and market participants.

Image: University of California