Abstract
A compact and simple structure is designed to create an all-optical XOR logic gate using a two-dimensional, photonic crystal lattice. The structure was implemented using three waveguides connected by two nano-resonators. The plane wave expansion method was used to obtain the photonic band gap and the finite-difference time-domain method was used to investigate the behavior of the electromagnetic field in the photonic crystal structure. Examining the high contrast ratio and high-speed cascade, all-optical XOR on a chip, the effects of fabrication error and the changes in the input optical power showed that the structure could be used in optical integrated circuits. The contrast ratio and data transfer rate of the cascade XOR logic gate were respectively obtained as 44.29 dB and 1.5 Tb/s. In addition, the designed structure had very small dimensions at 158.65 μm2 and required very low power to operate, which made it suitable for low-power circuits. This structure could also be used as a NOT logic gate. Therefore, an XNOR logic gate can be designed using XOR and NOT logic gates.
Highlights
Logic gates are devices that perform logical operations on one or more inputs and eventually generate one or more outputs
All-optical logic gates have attracted the attention of researchers due to their application in all-optical processing, the realization of all-optical computers, and the development of ultra-fast communication networks
Olyaee et al presented alloptical NOT and XOR logic gates based on the interference effect with high contrast ratios and low footprints
Summary
Logic gates are devices that perform logical operations on one or more inputs and eventually generate one or more outputs. The contrast ratios for AND and XOR logic gates were 12.78 and 5.66 dB, respectively. The proposed structures for NOT and XOR logic gates operated at three wavelengths of 1512, 1527, and 1544 nm, and the contrast ratio at best was 23.04 dB. A structure was introduced for various logic gates including AND, NOT, and XOR, which worked based on the interference effect [14]. Olyaee et al presented alloptical NOT and XOR logic gates based on the interference effect with high contrast ratios and low footprints. In addition to the structure design, the parameters that measure the performance of the designed logic gate in optical integrated circuits were investigated. The results showed that the designed logic gate could be effectively used in low-power optical integrated circuits.
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