The high field confinement in silicon core combined with superior miniaturization and low loss are some of the key features of using silicon waveguides for realizing integrated optical components. In addition, silicon has the best crystal quality and is the least expensive of all semiconductor materials.

On the other hand, all-optical logic gates (AOLGs), which overcome the fundamental barriers of their electronic counterparts, especially the limited speed of data handling and manipulation, are essential for the processing of information exclusively in the optical domain.

In this paper published in the Journal of Applied Physics, Amer Kotb from Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS), and his co-authors, Kyriakos Zoiros, from the Democritus University of Thrace, Xanthi 67100, Greece and Chunlei Guo from the Institute of Optics, University of Rochester, Rochester, New York 14627, USA, have employed E-shaped silicon-on-silica waveguide to investigate AOLGs, including XOR, AND, OR, NOT, NOR, NAND, and XNOR, at 1.55 μm telecommunication wavelength.

This waveguide is made up of four slots that are arranged to form the letter E. The working principle of these logic gates is based on the constructive and destructive interference incurred by the phase difference of the incident optical beams.

The performance of the target logic gates is assessed against the contrast ratio (CR) metric. Moreover, the dependence of the spectral transmission on the device’s key operating parameters is investigated and assessed.

Compared to other reported designs, the results obtained by conducting simulations using finite-difference-time-domain in Lumerical commercial software show that the proposed waveguide can operate at a higher speed of 80 Gb/s and attain higher CRs of 36 dB, 39 dB, 35.5 dB, 28.8 dB, 30 dB, 38 dB, and 36.7 dB for logic XOR, AND, OR, NOT, NOR, NAND, and XNOR, respectively.