There's absolutely no reason for the application you cited to optimize diameter and isn't approaching physical limits. There's no reason you can't shove many o

There's absolutely no reason for the application you cited to optimize diameter and isn't approaching physical limits. There's no reason you can't shove many optical fibers into that 5mm diameter. People don't, in short distance applications, to have simpler systems and connectors. There's big reasons why we don't use power over fiber (the endpoints are very expensive, and the overall system efficiencies are low). None of them have to do with the highest optical power density you could hit.