All‐Optical Demultiplexer/Multiplexer Based on Plasmonic Technology With Ultra‐High Transmission, Ultra‐Small Size, and Very High Modulation Depth

Photonic devices are of paramount importance in various fields, particularly in the realm of electronics. Nevertheless, miniaturization and the diffraction limit are the two issues that have plagued the development of photonic devices. Plasmonic devices solve these issues by enabling nanophotonics and nanodevices. A plasmonic demultiplexer/multiplexer is one of the essential all‐optical logic devices used in an all‐optical arithmetic logic unit (ALU). It is considered as a fundamental building block for all‐optical computers. In this work, an all‐optical demultiplexer (Demux) and multiplexer (Mux) based on ring insulator–metal–insulator (IMI) plasmonic waveguides are designed in a new structure. The area of the proposed design is minimal (300 × 300 nm), and it operates at a wavelength of 1550 nm. The transmission threshold between the logic 0 and 1 states in Demux and Mux is 0.5. Five parameters describe the performance of the plasmonic Demux and Mux; these parameters are transmission (T), extinction ratio (contrast ratio (CR)), modulation depth (MD), insertion loss (IL), and contrast loss (CL). The maximum transmission efficiency of the device is 203%, and the proposed structure dimensions are excellent and optimal according to the value of MD for Demux and Mux, which are 96.42% and 98.51%, respectively. The CR for Demux is 3.01, indicating a moderated level of performance. On the other hand, the CR for Mux is 2.568, which is considered adequate. Furthermore, the IL value is moderate for Demux and Mux, with respective values of 2.67 and 2.5, respectively. Moreover, the CL is considered appropriated for Demux and Mux, with values of 0.33 and 0.068, respectively. In addition, the minimum value of crosstalk (XT) in Demux is −11.55 dB. The proposed plasmonic Demux and Mux structure significantly contributes to the nanophotonic integrated circuits and all‐optical signal processing nanocircuits. The proposed plasmonic Mux is simulated by the finite element method (FEM) using COMSOL Multiphysics software.