Ultrafast all-optical OR gate using quantum-dot semiconductor optical amplifier-based Mach-Zehnder interferometer

Practical implementation of all-optical signal processing unit requires integrated all-optical devices for ease of manufacturing, installation, and operation. The semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is an integrated all-optical logic gate which can fulfill these requirements. Conceptually, SOA-MZI-based logic gate operation is straightforward, relying on optically inducing XGM, XPM or other nonlinear phenomena between the SOAs located in each of the two interferometer arms. In this paper, all-optical QD-SOA-based MZI switch is used to design the all-optical OR gate. The QD SOA-MZI operation has been analyzed theoretically by solving the rate equations of the QD-SOA dynamics, optical wave propagation equations in an active medium, and the MZI equations. The impact of the peak data power as well as of the QD-SOAs current density, maximum modal gain, and QD-SOAs length on the AM of the switching outcome are explored and assessed by means of the numerical simulation. The operation of the system is demonstrated with 160 Gbit/s.