All-optical logic gates using a plasmonic MIM waveguide and elliptical ring resonator

All - optical logic gates OR, XOR, AND and NOT based on two - dimensional ( 2D ) plasmonic metal - insulator - metal ( MIM ) coupled with Elliptical Ring Resonator ( ERR ) are presented , simulated and investigated by using the numerical method of the FEM (finite elements method ). The results are compared and validated with the finite difference time domain ( FDTD ) method . The proposed logic gates are achieved with the same structure using the constructive and destructive optical interferences between a control signal and input signal(s). Their characterization was mainly done for two spectral regions , visible and near - infrared . A high intensity contrast ratios (CR) between the logic states ( “1” and “0” ) can be achieved (28 dB ) at these spectral regions . We introduce a new parameter , "gap- threshold ratio ( GTR )", to characterize the gap between the maximum and minimum of the transmitted signal intensity for all logic gates. The suggested value of transmission threshold between logic 0 and logic 1 states is T th =0.2 . A comparison of the two parameters , (CR) and ( GTR ), with previous works shows that the proposed structure gives very good results for all logic gates configurations. The proposed all- optical logic gates configuration can be a key components in optical processing and telecommunication devices .

Optical Logic Gates Using A Graphene Clad Two Surface Plasmonic Polariton Mode Coupler for Optical Processor

An optical pulse controlled 2x2 two mode interference (OTMI) coupler having silicon core surrounded by Graphene clad has been introduced as fundamental gates of optical processing. Considering strong light –matter interactions and nonlinear optical property of graphene, we have shown coupling characteristics depending on additional phase change between the excited surface plasmon polariton modes propagating through the silicon core. By applying optical pulse energy of 0.82 pJ and width of 4 ps on graphene clad, the NOT, AND, and OR logic gates are demonstrated. The coupling length of the proposed device is ~ 3.2 times less than that of already reported optical device based on SPP modes. Our results promise to obtain the development of integrated of optical processor with high speed, compact and low power optical logic gates having high fabrication tolerance.

Ultrafast all optical XOR gate using photonic crystal-based nonlinear ring resonators

Optical logic gates can play crucial roles for designing all optical data processing circuits. Photonic crystals are one of the suitable platforms that can be used for designing all optical devices. In this paper an optical XOR gate was designed using nonlinear ring resonators. The proposed structure works are based on threshold switching. The working wavelength and the switching threshold of the resonators are 1550 nm and 1.8 W/μm2, respectively. The rise time is about 1 ps and the ON/OFF contrast ratio is about 16 dB.