To make the light travel enormous distances, thousands of volts of electricity are sent through the cable's copper sleeve to power repeaters, each the size and roughly the shape of a bluefin tuna.
Silicon photonics is a new approach to using light (photons) to move huge amounts of data at very high speeds with extremely low power over a thin optical fiber rather than using electrical signals over a coppercable.
The real advantage is that the lack of resistance means that a given thickness of superconducting cable can carry between two and ten times as much power as the same thickness of copper.