Research on silicon waveguide crossing for optical logic operations at telecommunication wavelength

Silicon (Si) waveguide crossing serves as an enabling technology for dense Si photonic integrated circuits. Efficient crossing designs significantly boost the performance of photonic devices with many crossings. In this paper, several fundamental optical logic functions, such as XOR, AND, OR, NOT, NOR, NAND, and XNOR, are reported at 1550 nm telecom wavelength using direct Si waveguide crossing. The proposed scheme is made up of three input waveguides and one output waveguide arranged in the shape of the symbol ' + ' with a microring resonator in the middle. The operation of the specified logic functions depends on the constructive and destructive interferences generated by the phase differences between the incident optical beams. Using the contrast ratio and amplitude modulation metrics, the performance of the target logic operations is evaluated. Additionally, it is investigated and assessed how much the critical operating parameters affect the spectrum transmission. The proposed waveguide-based scheme can achieve better performance compared to other reported designs of similar nature, according to simulation outcomes derived using Lumerical FDTD.