All-Optical Frequency Encoded Binary Half Subtractor Using Periodically Poled Lithium Niobate Waveguide and Reflecting Semiconductor Optical Amplifier

Optical data processors are the integral parts of an optical computer. Since the last few decades, many types of optical data processors were proposed based on different encoding principles such as intensity encoding, polarization encoding, phase encoding etc. Very recently, frequency encoding/decoding technique have also been well-established. The beauty of frequency encoding is that frequency is the fundamental identity of any signal; and it preserves its identity irrespective of reflection, refraction, absorption etc throughout the transmission of the signal. In this communication, the authors propose a method of developing half subtractor system adopting the frequency encoding technique. For this purpose, co-propagating beams having different frequencies in C-band are used for generating cascaded sum and difference frequency, exploiting the nonlinear response character of periodically poled LiNbO3 waveguide. The frequency conversion property of reflecting semiconductor optical amplifier (RSOA) and the frequency routing property of semiconductor optical amplifier (SOA) based optical add/drop multiplexer has been exploited here to obtain the desired half subtraction operation.