Simulation of an all optical full adder using optical switch

Abstract

The optical communication system has many advantages at long distance communication. Semiconductor optical amplifier based Mach Zehnder Interferometer plays an important role in fast optical communication. In this work the proposed SOA based MZI switch is used for all optical logic and arithmetic operations. In this architecture the continuous wave laser source and control signal pass through the Mach Zehnder Interferometer. Control signal at this wave length is split at the coupler and more power passes through one arm. The input data signal is fed to the coupler, which splits the signal equally. The resultant signals then propagates simultaneously through the two arms of the interferometer. This architecture can be used to perform all optical processing of signals like half adder, full adder, de multiplexer etc. MZI switch is a very powerful technique to realize ultrafast switching. The physical mechanism behind the working of MZI switch is cross-phase modulation (XPM). Here the gain saturation induced by beam reduces carrier density inside one SOA, which in turn increases the refractive index only in the arm through which the light passes. As a result, an additional phase shift can be introduced on the CW beam because of the XPM, and the CW wave is directed towards the bar port during each one bit. Now it is clear that in the absence of control signal, the incoming signal (CW signal) exits through the cross port (lower channel) of MZI. In this case no light is present in the bar port. But in the presence of the control signal, the incoming signal exits through the bar port of the MZI.