Silicon-on-insulator (SOI) is an optical structure created by a thin layer of silicon (Si) patterned on an insulating layer, commonly silicon dioxide (SiO₂). Because of the remarkable transparency of Si in the infrared band and the significant refractive index difference between Si and SiO₂, SOI waveguides have unique optical features.

On the other hand, the development of all-optical logic technologies is fundamental to realize future telecommunication networks with the exponential growth of internet traffic.

In this paper published in Optical Engineering, Amer Kotb from Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS), Changchun 13033, China and his co-author, Chaonan Yao, from the Hisense Broadband Multimedia Technologies Co., Ltd., Qingdao 266100, China have simulated a complete family of the basic all-optical logic operations, including XOR, AND, OR, NOT, NOR, NAND, and XNOR using SOI waveguides at 1.33 μm telecommunication wavelength.

The suggested waveguide consists of two microring resonators and three strips, all made of Si patterned on SiO₂. The operation principle for the realization of the proposed logic operations depends on the constructive and destructive interferences between the incident beams.

These logic gates have been implemented by running Lumerical finite-difference-time-domain solutions with the convolutional optimally matched layer as an absorbing boundary condition.

The dependence of the device performance on the key operating parameters is investigated and assessed. The simulation results indicated that all-optical logic gates can be executed using the proposed compact structure with higher contrast ratios than other reported designs.