Now, an advance in optical communication that will reduce costs of fiber-based backhaul

Posted on June 26, 2015  /  0 Comments

While we are fully sympathetic with a focus on wireless in the access network, we have for long been advocates of bringing optical fiber as close as possible to the user and for moving from point-to-point or ring architectures in current fiber networks to mesh architectures. In this context, reports of a breakthrough in optical communication makes us happy. Of course, we understand it takes a little while to go from the pages of Science to reducing repeaters in actual optical fiber cables.

One way to understand the challenge of sending data through fiber-optic circuits is to imagine a person shouting to someone else down a long corridor. As the listener moves farther away, the words become fainter and more difficult to discern as they echo off the walls.

A similar challenge confronts the designers of networks that carry data. Beams of laser light packed densely in fiber-optic glass wires need to be both amplified and recreated at regular intervals to send them thousands of miles. The process of converting the optical ones from light to electricity and then back again roughly every 60 miles is a significant part of the cost of these networks. The process also limits how much data they can carry.

In its report, the group described a way to “predistort” the data that is transmitted via laser beams so that it can be deciphered easily over great distances.

This is done by creating, in effect, guardrails for the light beams with a device known as a frequency comb — using very precise and evenly spaced signals — to encode the information before it is transmitted.

That has the effect of embedding a digital watermark in the original data, making it possible to transmit data accurately over much longer distances and dispense with the need to perform optical-to-electronic conversions at relatively short intervals.


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