Modulation Bandwidth Enhancement in Optical Injection-Locked Semiconductor Ring Laser

The modulation bandwidth of a optical injection-locked (OIL) master-slave configuration using a semiconductor ring laser (SRL) as the slave laser is investigated. The modulation bandwidth depends on the detuning frequency, input optical power into the slave SRL, and the bias current to the SRL in the master-slave configuration. Modulation bandwidth of >40 GHz has been achieved when modulating the master laser, in contrast to the 15-GHz modulation bandwidth of the free-running SRL. The unidirectional operation of the SRL as a slave laser allows monolithic integration of such OIL scheme as it produces little feedback to the master laser.