Novel all-optical implementations for logic AND and XOR gates are experimentally demonstrated at 2.5Gb/s based on
cavity-enhanced four-wave-mixing (CE-FWM) combined with optical injection locking phenomena in monolithically
integrated semiconductor ring lasers (SRLs). All-optical AND gate with simultaneous wavelength conversion have been
achieved using the CE-FWM. XOR function is demonstrated using two parallel SRLs, each performing one part of XOR
Boolean equation A ⊕B = A B¯ + AB¯ . Error-free operation with extinction ratio higher than 10dB confirms the
suitability of SRLs for all-optical logic applications.
In this paper, we propose and experimentally demonstrate an all-optical non-return-to-zero (NRZ) to return-to-zero (RZ)
format conversion using semiconductor ring laser (SRL). A 155Mb/s NRZ optical data signal is injected into the
counterclockwise (CCW) direction of the SRL and an optical logic clock signal is injected to the clockwise (CW)
propagation direction. The power and wavelength on both sides are adjusted so that during the 'high' level of the clock,
the SRL is held to the CW direction regardless of the logic value of the corresponding data bit. The SRL will only be
switched to the CCW direction when the input data is 'high' and when the clock level is 'low'. Therefore the NRZ
format signal is converted to RZ format signal, with a duty cycle decided by the duty cycle of the optical clock.
Extinction ratio of > 10 dB has been achieved and the scheme can also be used for all-optical 3R. Although the speed of
the signal is yet limited, higher speed can be achieved with faster SRL devices.