All Optical Frequency Encoded AND Gate Using SOAs and Intensity Switch

In this paper, we present a novel all optical frequency encoded AND gate using two travelling wave Semiconductor Optical Amplifiers (TW-SOAs), optical WDM multiplexer and Intensity Switch that can be put to operation using CW laser inputs. We confirm its operation using simulation in Optisystem software. The frequency encoded system utilizes two different frequencies to represent logic 0 and logic 1 instead of intensity variation and has numerous established advantages over other encoding techniques. We successfully simulated the proposed AND gate and the results thus obtained satisfy the truth table. The SOA has been used to specifically exploit its nonlinearities, viz., nonlinear gain spectrum and cross gain modulation (XGM). Former signifies the fact that the gain of a SOA is highest at a particular wavelength and reduces on both sides away from the gain peak wavelength, while the latter signifies that a signal at one wavelength affects the gain of signal at another wavelength passing through the SOA due to its gain saturation properties. The intensity switch is a recently invented device that can be used to separate high from low intensity signals on basis of principles of nonlinear optics.