Ultra-fast all-optical ADC using nonlinear ring resonators in photonic crystal microstructure

In this paper, we report a new design of a two-bit all-optical analog-to-digital converter (ADC) based on photonic crystal ring resonators. The photonic crystal structure has a square lattice of silicon rods, and four ring resonators carry out sampling and quantizing with linear and nonlinear rods at a wavelength of 1550 nm. Our calculations reveal that the proposed ADC has a maximum response time of about 4 ps and a sampling rate of 125 GS/s that is much faster than the ADC in previous studies. The proposed ADC also has a small area (called footprint) with a minimum leakage loss, considered the most suitable device in photonic integrated circuits.