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Given the cost of laying fiber lines across the ocean and this tech (appears) to double the capacity of an existing line, why would there not be a push to get t

by billme 6y ago

Given the cost of laying fiber lines across the ocean and this tech (appears) to double the capacity of an existing line, why would there not be a push to get this into use, what am I missing?

detaro 6y ago
This is a field that's constantly being worked on, not sure why you say there isn't a "push" in it. This specific thing is not faster than previous results, but more compact. Long-distance fiber lines also have amplifiers along the way, so you can't just scale them up by changing the endpoints if it doesn't match the capability of the in-line hardware.
- billme 6y ago
  Cost of swapping the amplifiers, not just the end-points, makes sense as an issue. Thanks! As for it being “only more compact” not a capacity increase, for a comparable single coherent optical fiber line, are existing fibers filled to capacity due to the limits of tech, economies, physics, etc. - if physics, then I assume all fibers are at capacity, right?
  - dasudasu 6y ago
    If you're going to lay a fiber across the oceans, then yeah, that capacity is going to approach the Shannon limit, but at some point there is a calculation to be made about how expensive it is to use all that capacity vs using multi-core fibers or just laying out more fibers. The economics of it are pretty interesting. A single fiber (non-submarine) is about ¢8 a meter in raw cost, and it said that they laid out so many during the telecom bubble of the late 1990s that there are still many unused (so-called dark) fiber networks throughout the US. See for example https://www.ofsoptics.com/lighting-up-dark-fiber/ https://www.ofsoptics.com/lighting-up-dark-fiber/
- cycomanic 6y ago
  That is incorrect the amplifiers have the capacity to amplify lots of channels simultaneously. So it is sufficient to only upgrade the endpoints (unless your fibre is full, where full means the bandwidth of the amplifiers, ~100 Tb/s for a single fibre). This has in fact been the driver behind the tremendous growth in data rates we have seen in the last 30 years. Operators can incrementally upgrade links by upgrading the endpoints. To transfer a MB across the network was 100s of $ in the 90s and is now essentially free (it's like 10e-4 cents or sol
- eternauta3k 6y ago
  When do you have to replace an EDFA?

by billme 6y ago

Given the cost of laying fiber lines across the ocean and this tech (appears) to double the capacity of an existing line, why would there not be a push to get this into use, what am I missing?

detaro 6y ago

This is a field that's constantly being worked on, not sure why you say there isn't a "push" in it. This specific thing is not faster than previous results, but more compact. Long-distance fiber lines also have amplifiers along the way, so you can't just scale them up by changing the endpoints if it doesn't match the capability of the in-line hardware.

billme 6y ago
Cost of swapping the amplifiers, not just the end-points, makes sense as an issue. Thanks! As for it being “only more compact” not a capacity increase, for a comparable single coherent optical fiber line, are existing fibers filled to capacity due to the limits of tech, economies, physics, etc. - if physics, then I assume all fibers are at capacity, right?
- dasudasu 6y ago
  If you're going to lay a fiber across the oceans, then yeah, that capacity is going to approach the Shannon limit, but at some point there is a calculation to be made about how expensive it is to use all that capacity vs using multi-core fibers or just laying out more fibers. The economics of it are pretty interesting. A single fiber (non-submarine) is about ¢8 a meter in raw cost, and it said that they laid out so many during the telecom bubble of the late 1990s that there are still many unused (so-called dark) fiber networks throughout the US. See for example https://www.ofsoptics.com/lighting-up-dark-fiber/ https://www.ofsoptics.com/lighting-up-dark-fiber/
cycomanic 6y ago
That is incorrect the amplifiers have the capacity to amplify lots of channels simultaneously. So it is sufficient to only upgrade the endpoints (unless your fibre is full, where full means the bandwidth of the amplifiers, ~100 Tb/s for a single fibre). This has in fact been the driver behind the tremendous growth in data rates we have seen in the last 30 years. Operators can incrementally upgrade links by upgrading the endpoints. To transfer a MB across the network was 100s of $ in the 90s and is now essentially free (it's like 10e-4 cents or sol
eternauta3k 6y ago
When do you have to replace an EDFA?