The point with transformation of electrical into optical signals and vice versa is the highest possible precision at the connection between glass fibre and electronic modules.

It is only the core of the fibre, with a few micrometres just as thick as the fraction of a hair, that may effectively transmit the laser light. Since information is thus transported only through the fibre core, its position relative to the module has to be precisely adjusted.

Subsequently, the link is fixed with welding points generated by a laser.