High-Performance All-Optical Logic Operations Using Ψ-Shaped Silicon Waveguides at 1.55 μm

Abstract

We simulate with FDTD solutions a complete family of basic Boolean logic operations, which includes XOR, AND, OR, NOT, NOR, NAND, and XNOR, by using compact Ψ-shaped silicon-on-silica optical waveguides that are operated at a 1.55 μm telecommunications wavelength. Four identical slots and one microring resonator, all made of silicon deposited on silica, compose the adopted waveguide. The operating principle of these logic gates is based on the constructive and destructive interferences that result from the phase differences incurred by the launched input optical beams. The performance of these logic operations is evaluated against the contrast ratio (CR) metric. The obtained results suggest that the considered functions designed with the employed waveguide can be realized all-optically with higher CRs and faster speeds than other reported designs.

All-Optical XOR, AND, OR, NOT, NOR, NAND, and XNOR Logic Operations Based on M-Shaped Silicon Waveguides at 1.55 μm

“…The simulation findings show that the examined logic functions generated when using the suggested waveguide can be achieved with higher CRs when compared to other reported designs [ 11 , 16 , 17 , 18 , 22 , 23 , 34 , 35 , 40 , 41 ] (see Table 8). These findings complement and generalize our relevant research that has been conducted so far [ 26 , 27 , 28 , 29 , 30 , 31 ], and essentially extends the technological suite in the quest for providing different design and building options for Si waveguide-based core logic modules.…”

“…A transverse magnetic (TM) mode polarized pulse at 1.55 μm excites the input ports. The outcomes of the simulations are captured by setting FDTD monitors, i.e., , where I out is the intensity at the output port (i.e., port 4), and , which is the sum of the intensities at three input ports [ 26 , 27 , 28 , 29 , 30 , 31 ]. The value of 0.2 is assigned to the normalized threshold transmission (T th ), which is the minimum normalized power required to generate T. To optimize T, the incident beams have to meet suitable phase-matching conditions [ 44 , 45 ].…”

“…On the other hand, optical logic operations can have potential advantages in terms of speed and energy efficiency as compared to traditional electronic circuits [ 9 , 10 ]. Indeed, optical logic gates have recently been designed and/or constructed utilizing a variety of waveguide designs [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Implementing complete optical computing systems based on optical logic functions is a challenging task because it involves maintaining signal integrity over long distances, dealing with issues such as signal loss and dispersion, and developing practical devices that can be integrated into larger systems.…”

“…Four identical slots, configured in the shape of the letter ‘M’, comprise the suggested waveguide; these slots are all composed of Si on top of SiO 2 . Compared to our pervious Si designs [ 26 , 27 , 28 , 29 , 30 , 31 ], this proposed waveguide is easier to use in the communications network, as well as in the design of many computational logic circuits. The variety of waveguide designs allows engineers and designers to choose the most appropriate structure for a given application, taking into account factors like frequency range, mode handling, size, polarization, materials, manufacturing constraints, and specialized requirements.…”

“…In this paper, the logic operations work is based on constructive interference (CI) and destructive interference (DI) that results from the input optical beams’ phase variations. The performance of the logic operations is evaluated utilizing the contrast ratio (CR) metric [ 26 , 27 , 28 , 29 , 30 , 31 ] through Lumerical finite-difference-time-domain (FDTD) solutions [ 42 ], with the convolutional perfectly matched layer (PML) as an absorbing boundary condition [ 43 ]. The incident light will be absorbed with a minimal number of reflections under the PML absorbing boundary conditions.…”