A theoretical analysis of optical phase-lock loop acquisition and tracking for WDM receiver applications

The acquisition and tracking characteristics of optical phase-lock loops for WDM receiver applications are theoretically analyzed in this work. As the locking bandwidth is controlled by a convenient design of the feedback loop, an optical WDM channel, whose frequency lies within the receiver locking range, can induce the locking of a slave semiconductor laser and be properly detected without the need for optical filters. Other carriers are discarded by the loop electronics bandwidth. The receiver modeling takes into account the loop feedback effect over the slave laser rate equations, allowing a time-dependent analysis of the locking process. Once locking is acquired, the model also allows the analysis of the loop tracking during WDM channel frequency modulation.