Electrooptical Comparator: From Formula to Implementation

This paper is concerned with a process of transforming the mathematical representation of a multithreshold comparator to electrooptical implementations. The basic comparator converts an analog input into one of two levels at its (binary) output. If this functionality can be made periodic (as a function of the analog input), efficient implementation of analog-to-digital conversion can be realized. This paper begins by modeling such functionality as a square-wave via its representation as a Fourier series. Some mathematical manipulations are then performed aimed at tailoring the obtained representation for implementation by optical components such as waveguides and microring resonators. Thus, three basic integrated-optical devices are proposed for realizing a comparator with well-defined binary output levels and a steep transition slope between these levels.