On superluminal tunneling

Photonic tunneling is currently of theoretical and applied interest. In a previous review, faster-than-light (i.e. superluminal) photonic tunneling was discussed (Progr. Quantum Electron. 21 (1997) 81). Recently, superluminal photonic pulse transmission and reflection have been measured at microwave and infrared frequencies. It seems clear that superluminal photonic and electronic devices will become a reality in the near future. present report, we introduce new experimental and theoretical data on superluminal tunneling and reflection. Data of reflection by barriers have evidenced the nonlocal nature of tunneling. Asymmetric barriers have revealed a strange asymmetric reflection behavior in time. inciple of causality is not violated by a superluminal speed even though the time duration between cause and effect can be shortened compared with a luminal interaction exchange. An empirical relationship independent of the barrier system is found for the photonic tunneling time. This relation seems to be universal for all kind of tunneling processes in the case of single opaque barriers. We show that the superluminal velocity can be applied to speed up photonic modulation and transmission as well as to improve microelectronic devices.