All-optical digital logic AND and XOR gates using four-wave-mixing in monolithically integrated semiconductor ring lasers

Novel all-optical implementations for logic AND and XOR gates are experimentally demonstrated at 2.5 Gbit/s based on cavity-enhanced four-wave-mixing (CE-FWM) combined with optical injection locking phenomena in monolithically integrated semiconductor ring lasers (SRLs). An all-optical AND gate with simultaneous wavelength conversion has been achieved using CE-FWM. An XOR function is demonstrated using two parallel SRLs, each performing one part of the XOR Boolean equation A oplus B=ABmacr +AmacrB. Error-free operation with extinction ratio higher than 10 dB confirms the suitability of SRLs for all-optical logic applications.