Plasmonic modulation and switching via combined utilization of Young interference and metal–insulator–metal waveguide coupling

We present a new nanoscale modulation scheme based on the formation of a plasmonic Young interference pattern and its collection by an excitation field pattern-sensitive metal–insulator–metal (MIM) waveguide. Our numerical investigations reveal that such a scheme can generate sensitive and quasi-linear changes in the output power level in response to the relative phase difference between the waves in the two Young interferometer branches. Thanks to the asymmetric positioning of the collector waveguide, the response becomes most sensitive and linear when the relative phase difference is close to zero. Such a response characteristic can benefit future plasmonic systems by eliminating the need for phase prebiasing. The strong interactions between the surface plasmon polaritons inside the MIM structures are also utilized for realizing functionalities beyond modulation, such as on/off modulation contrast enhancement and all-plasmonic and logic operation.