Pulse splitting and superposition in linear systems

Kuan-Ren Chen^1*, Alex.E.Chen¹, Jian-Shiung Hong¹

¹Department of Physics, National Cheng-Kung University, Tainan, Taiwan

* Presenter:Kuan-Ren Chen, email:chenkr@phys.ncku.edu.tw

Pulse splitting requires nonlinearity while the principle of superposition demands linear consequences. Here, we demonstrate that, in linear systems with no known nonlinearities, pulse can split and superposition can cause nonlinear consequences. We investigated the transmission of a light pulse through and the reflection within a plasmonic subwavelength slit. The slit, pierced in a metallic film to maintain the light coherence and self-consistency, and the interfaces provide the spatial boundary conditions for manipulating light phase according with linear Maxwell’s equations. We find that the transmission through the slit entrance causes a phase change depending on the light frequency and thus the splitting of the pulse, with or without including the effects from the disparity of group velocity due to dispersion. We further study the reflections within the slit and the resultant superposition of fundamental modes or sub-pulses in phase to cause nonlinear consequences. An analytical theory is derived to illuminate the key underneath new physical mechanism.

Keywords: Plasmonics, Non-linear, Fundamental