Analysis of the automatic frequency control in heterodyne optical receivers

A theoretical analysis of the automatic frequency control (AFC) in binary DPSK and FSK heterodyne optical receivers is presented, and its impact on the system performance is evaluated. The effects of the shot-noise AM/FM conversion in the frequency discriminator are analyzed. It is shown that with commercial DFB lasers a common analysis of the frequency control loop can be done for the three modulations considered. Design guidelines are given that account for the presence of the AFC loop by properly using some performance results derived in the assumption of perfect frequency tracking.<
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