Digitally Integrated Self-Trained Predistortion Curve Finder for Passive Sweep Linearization of Semiconductor Lasers

This paper reports a digitally integrated, self-trained predistortion curve finder for linearly frequency-swept semiconductor lasers. In this method, we introduce an iteration machine to train the laser current curves by utilizing the feedback signals from the laser's output. By measuring the phase and frequency information of lasers, we find that the predistortion finder in our design can generate various high sweep velocities (THz/ms) of lasers in 1 s with phase error range less than π/2. This method is universal for semiconductor lasers at any sweep frequency velocity.