Design and analysis of all-optical half-adder, half-subtractor and 4-bit decoder based on SOA-MZI configuration

Abstract

In the paper, all-optical Boolean circuits implemented with a semiconductor optical amplifier based Mach–Zehnder interferometer, are simulated and analyzed at 10 Gb/s to extract a simple design rule. Authors propose the novel designs of half-adder, half-subtractor and 4-bit decoder for various results and also discussed the results at different bit rates. In the designs, one data acts as a pump generated through clock wave laser and another acts as a probe from mode lock laser. The designs consist of non-linearity in semiconductor optical amplifier using the cross gain modulation technique. Cross gain modulation refers to data on pump signal modulating the carrier density in semiconductor optical amplifier. At the same time, the gain variation indentation inverts the probe signal after passing through amplifier. Interferometer structure is used to convert the phase modulation into intensity modulation. The paper aims to achieve the goal through simulation and Boolean analysis in terms of gates, to provide simple design rule. Obtained results are very useful in the design of other more complex all-optical circuits that employ the given gates as the basic building block. The extinction ratio is the optimization criteria for all the three circuits at different values of pump power and bit rate of input pulse.