Photorefractive Effect in Plasmonic Waveguides

In this paper, for the first time, the photorefractive effect in plasmonic waveguides is theoretically modeled and investigated in detail. A metal- LiNbO₃-metal nanostructure is considered, with the LiNbO₃ being doped with donor and acceptor impurities. The interaction between symmetric and antisymmetric interfering SPP modes is studied. It is shown that a strong symmetric mode can be coupled to a week antisymmetric mode by the mean of photorefractive effect. When the modal losses are taken into account, it was found that losses can limit the interaction length. However, by choosing the proper waveguide length, doping concentration, and amplitude inputs, the photorefractive coupling process is shown yet to be viable despite losses. The coupling effect can be conducted either as an amplification or mode conversion process, promising novel future application. For instant, several known photorefractive applications in microphotonics can be borrowed and implemented in the plasmonic field.