Numerical analysis of all-optical analog-to-digital converter (AO-ADC) using ring resonators on the integrated photonic platform

This paper investigates a 2-bit all-optical analog-to-digital converter (AO-ADC) using the photonic crystal (PhC) structure. The proposed structure comprises a 27 × 27 grid of silicon rods in air with a refractive index of 3.6. In the design of this converter, a linear demultiplexer and an optical encoder are used. The optical demultiplexer has one input and three outputs. Optical coding has three inputs and two outputs. In general, this converter consists of one input and two outputs, and according to the output light power from the structure and the threshold level of the converter, two logical 0 and 1 states are created in the output. The footprint of the proposed AO-ADC is as small as 118.5 µm² making it more suitable for use in the optical integrated circuits (OICs) compared to the previous structures. The proposed AO-ADC works at an operating wavelength of 1550 nm with a response time of about 0.6 ps and also works with lower optical intensity.