High frequency modeling and characterization of high performance DFB laser modules

The paper describes the high frequency design of DFB laser transmitter modules with modulation bandwidth in excess of 10 GHz, manufactured and tested for coherent optical transmission experiments. The method is based on a previous conventional small-signal analysis of the parasitics (package and laser chip) and the active region dynamics, solving the two associated equivalent circuits by comparing, respectively, the measured electrical reflection and optical noise responses to the corresponding computed microwave simulations, Then, suitably combining the two circuits, the complete and independent model of the transmitter module is derived, which allows the final, more precise and complete determination of any circuit element with simulated modulation responses in good agreement with the experimental results. Finally, an example of optimization of the package high frequency performance, carried out by the aid of the developed model, and supported by a time-domain reflection analysis, is presented