Not sure how optics would help. If your wire has some kind of side channel, optics can have it too. If you want to detect stray mysterious photons then you could do the same with electrons.

But in any case, this is not really the level of concern here. It's equipment that tampers with the device. The only way to be sure is to roll your own. Which holds for both sides. So the perfect systems needs to be created by two adverse parties, which means it's impossible to do. Qed.

(In the real world with physical proof this is different since tampering is much harder and it's a problem worked on for centuries. It's not bullet proof either but much more mature.)