Method of implementation of all-optical frequency encoded logic operations exploiting the propagation characters of light through semiconductor optical amplifiers

Abstract

Optics has already proved its strong potentiality for conducting parallel logic, arithmetic and algebraic operations. Since last few decades so many all-optical data processors were proposed. To implement these processors different encoding / decoding techniques, such as polarization encoding, intensity encoding, phase encoding technique have been reported. Very recently ‘frequency encoding’ technique have drawn a special interest to the scientific community. The frequency is the fundamental character of a signal and it preserves its identity irrespective of reflection, refraction, transmission, absorption throughout the communication. Therefore, if two specific frequencies are encoded as 1 state and 0 states respectively, then one can ensure about the state of information throughout the communications. In this paper the authors propose a method of conducting inversion OR, NOR and NAND logic operations exploiting the wavelength conversion, which is achieved by exploiting the cross gain modulation (XGM) property of reflecting semiconductor optical amplifier (RSOA), as well as the property of change of nonlinear rotation of the state of polarization of probe beam by cross phase modulation (XPM). Both the wavelength conversion properties are controlled by the intensity of the pump beam. The major advantage of SOA-switching over any other conventional switching is that SOA-switching require low power with good on off contrast ratio. Again as the NAND and NOR are the universal logic gates, so any other logic operation can be implemented using this concept.