  Photonic tunneling permits superluminal signal transmission. The principle of
causality is not violated but the time duration between cause and effect can be
shortened compared with an interaction exchange with velocity of light. This
outstanding property can be applied to speed-up photonic signal modulation and
transmission as well as to improve micro-electronic devices. Superluminal
photonic signal transmission have been presented at microwave and infrared
frequencies already. Presumably superluminal photonic and electronic devices
can become reality having in mind the experimental evidence of the universal
tunneling time of photons and of electrons.
