Ultra-fast 1-bit comparator using nonlinear photonic crystalbased ring resonators

In this paper, a photonic crystal structure for comparing two bits has been proposed. This structure includes four resonant rings and some nonlinear rods. The nonlinear rods used inside the resonant rings were made of a doped glass whose linear and nonlinear refractive indices are 1.4 and 10-14 m2/W, respectively. Using Kerr effect, optical waves are guided toward the correct output ports. In this study, plane wave expansion and finite difference time domain methods were used for calculation of photonic bandgap and simulation of optical wave propagation, respectively. The size of the proposed structure is 1585 μm2 which is more compact than the previous works. Furthermore, the obtained maximum delay time is about 2 ps that is proper to highspeed processing. The normalized output power margins for logic 0 and 1 are calculated as 25% and 71%, respectively. According to the obtained results, this structure can be used for optical integrated circuits.