All-optical quaternary logic gates – An extension of binary logic gates

•Proposed optical circuit is dedicated to implement any two-input quaternary logic.•Binary logic operations are done among the equivalent binary data using PSW.•Then intensity encoded data are converted into frequency encoded data.•Simulation result supports the feasibility of the proposed scheme.

All optical multivalued logic processors are of paramount importance in optical computing and signal processing. In this communication, the author proposes a new method of developing all-optical quaternary logic gates which are the extension of binary logic gates. To develop the quaternary logic gate the authors first coverts the quaternary frequency encoded data into equivalent binary intensity encoded data; then binary logic operations are done among the equivalent binary data, and finally the intensity encoded data outputs are converted into frequency encoded quaternary logic output. Simulation result supports the feasibility of the proposed scheme. Novelty of the scheme is that the same optical circuit is dedicated to implement any two-input quaternary logic operation only by changing two basic switches functioning as binary logic gates. Finally, the authors have cascaded these logic gates using “1×2” all-optical switches to develop quaternary logic unit by means of which any kind of quaternary logic operation as proposed in this scheme can be performed. Dense wavelength division demultiplexers (DMUX) are used here for wavelength routing purpose, and switching and frequency conversion characters of semiconductor optical amplifiers are exploited to develop very fast and secure quaternary logic unit.