In both cases it's EM waves that are traveling. In 'electronics,' mobile electrons normally guide the EM waves, which are typically 0-10GHz in frequency. In 'op

In both cases it's EM waves that are traveling. In 'electronics,' mobile electrons normally guide the EM waves, which are typically 0-10GHz in frequency. In 'optics,' bound electrons normally guide the EM waves, which are typically hundreds of THz in frequency. In either case, you make a switch by somehow reversibly spoiling the waveguide that connects point A with point B. Collisions between electrons don't directly affect either picture. You can multiplex lots and lots of completely independent 'electronic' EM waves on one conductor, they pass right through each other exactly as you described for optics, no problem. The advantage of optics is that the low-loss bandwidth of optical waveguides is enormously wider than the low-loss bandwidth of waveguides made using copper or other conductors. And with optics we have enormous bandwidth available. One disadvantage of optics is that we don't have a low-lag way to interconnect switches. We can connect switches, but so far the interconnect delays are much, much longer than the switching times. So a fast optical switch is useful, but so far only in systems that are solely "feed forward," like communication.