All-optical OR/XOR logic gate using PhC-based T-shaped waveguide with high-contrast output to implement 3-bit binary to gray code converter

In this article, a theoretical analysis on T-shaped waveguide is performed using coupled mode theory which admits its operation as power combiner, splitter and diverter. These applications of the waveguide can very well be utilized to project it as OR and XOR logic gates. In order to achieve this, the T-shaped waveguide is mapped onto the photonic crystal of square-type lattice and the validity is observed with the theoretical analysis. Later, the designed T-shaped waveguide is used to define OR and XOR gates, which results in the contrast ratio and response time of 54.43 dB and < 1 ps, respectively, at 1550 nm. Further, the higher contrast ratio of the T-shaped waveguide-based XOR logic gate allows it to cascade with itself in a single stage to realize a 3-bit binary to gray code converter. The simulation results show that the code converter operates with contrast ratio of above 9.82 dB at the output ports. Finally, the fair results obtained from theoretical analysis and numerical simulation conclude that the T-shaped waveguide can be a potential component as logic gate in the future photonic integrated circuits.