All-optical NRZ to RZ format conversion using bistable semiconductor ring laser

摘要

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.