Gain-assisted magnetoplasmonic switching in metal-dielectric-metal plasmonic waveguides

Optical switches in metal-dielectric-metal (MIM) structures attracted much interest for chip-scale plasmonic modulator merging nanoelectronics and ultrafast photonics. The absorption switches employed gain modulations; thus, their switching speed is limited to the sub-gigahertz range because of the spontaneous lifetime of the transition. In this paper, we theoretically predicted that the function of the absorption switches is achieved employing magnetic field reversal and constant gain instead of gain modulations. We investigated analytically and numerically transmission in the presence of both gain and gyration and revealed that the transmission shift by the external magnetic field is maximized at a resonance value of gain. The switching speed can reach the THz range thanks to the large optical bandwidth in the MIM stub structures and the advanced magnetization switching technology. The MIM structure with combined gain and magnetoplasmonic properties enhances interaction between light and magnetic field on nanoscale and enables the device footprint down to the deep subwavelength scale lambda(2) / 50.