Distributed Parametric Effect in Long Lines and its Applications
  The article considers a parametric effect which takes place when the velocity of signal propagation in a long line changes. We found the analytical solution describing the form of the transformed signal for a line with losses, when line parameters change symmetrically. We also considered lines without losses, with asymmetrical change of parameters. Our theoretical results comply with experimental data. In certain conditions, such a line can be used as an amplifier. The parametric effect in optics is described by Maxwell's equations, while in case of a long line, the analysis is based on telegrapher's equations. However, it turns out that in the end, both in optics and electronics, the parametric effect is described by wave equations that are mathematically similar. This is because fundamentally, the parametric effect is physically based on energy interchange between the controlling (pump) signal and the transformed one, when the parameters of the propagating medium change. So, the obtained results can be used for analysis of parametric effects in optics and electronics. 
Yu. K. Shestopaloff
physics.gen-ph