Due to the significant infrared transparency of silicon and refractive index difference between silicon (i.e. core with n_silicon ≈ 3.48 at 1.55 μm) and silica (i.e. cladding with n_silica ≈ 1.444 at 1.55 μm), silicon-on-silica optical waveguides have unique optical features.

By enabling the execution of signal processing functionalities without troublesome optoelectronic conversions at the photonic nodes, all-optical gates serve as essential building blocks for the construction of lightwave broadband communications networks.

Therefore, Amer Kotb at Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) and his co-author, Kyriakos Zoiros, at the Democritus University of Thrace have simulated seven basic logic operations, including XOR, AND, OR, NOT, NOR, NAND, and XNOR, using K-shaped silicon-on-silica waveguides operated at a telecommunications wavelength of 1.55 μm.

The interferences, both constructive and destructive, that are created by the phase difference between the input beams, creates are the key for the realization of the considered logic operations.

In order to demonstrate how the logic operations are executed FDTD solutions are obtained, using commercially available software, with the convolutional optimally matched layer as an absorbing boundary condition. The logic operations’ performance is assessed against the contrast ratio (CR) metric.

According to the derived simulation results published in Electronics, the employed waveguide can achieve higher CRs at an extended data rate of 120 Gb/s, and hence can outperform previously reported designs.