All-Optical switching in metal nanoparticles plasmonic waveguide using EIT phenomenon

In this work an all-optical switch based on array of metal nanoparticles (MNP), imbedded in a medium which shows Electromagnetically Induced Transparency (EIT), has been proposed. By implementing EIT in the host medium of MNP plasmonic waveguide, we can induce a transparency and alter the refractive index, by applying reasonable values of optical pumps. Using Finite-Difference Time-Domain (FDTD) simulation, it is found that the proposed all-optical switching exhibits femtosecond-scale feedback time. Results show that the response time of signal light switching up and down are about 100 fs. The proposed switch has a signal transmission of about 14% for a chain of 20 silver MNPs with a length of about 3 μm. It shows losses about 7.75 dB/μm. The proposed nanoscale plasmonic switch has optical properties that cannot be achieved in any other ways at the nanometer scale, such as overcoming diffraction limit.