if somebody can explain me how you can transfer TTL trough fibers?(how the length of the discharges can be controlled?)
With electrical signals you can start the strobe with the X and cut it off (IGBT) with the Q signal, off coarse when the strobe is build for it.
Well, i actually meant that if you go the length having a pic-controlled led flash, i suppose it is doing some form of i/eTTL in the sense that it is performing pre flashes as well as reacting at the cut-off signal. If you have a underwater strobe that is said to do optical TTL, that will be enough to let the camera controll the strobe's output.
I don't know but I don't thing that any manufacturer has implemented a TTL protocol for fibre, but it would be useful with a standardized data format based on messages rather than propriatory pin configurations and propitiatory data interchange.
I made a triggerflash a year ago, but it is just dumb just using the 1ms camera trigger pulse.