Tunnel filters and optical amplifiers for use in fiber optic communication systems

Abstract

Tunneling through a potential barrier is a well-known concept in quantum mechanics. It is shown that tunneling is not an inherently quantum-mechanical phenomenon but that it occurs in classical optics as well. Single-layer and double-layer dielectrics in which optical tunneling occurs are shown to serve as the basis of optical filters, the double-layer tunnel filter having a much higher resolution capability than the single-layer tunnel filter. Optical amplifiers used as a receiver preamplifier and as linear intermediate repeaters are evaluated. Performance parameters of particular interest are the receiver sensitivity and the total system gain. The effects of optical amplifier gain and bandwidth on those parameters are studied. Finally, the effects of gain variations are considered. It is shown that gain control gives very poor results, whereas power control does not severely limit the system performance, particularly when a small number of amplifiers are used.