A complete small-signal equivalent circuit model of cooled butterfly-type 2.5 Gbps DFB laser modules and its application to improve high frequency characteristics

A small-signal equivalent circuit model of 2.5 Gbps DFB laser modules with butterfly-type dual-in-line packages has been proposed and verified using extracted parameters. Parameters related to the equivalent circuit have been extracted from measured S parameters using the modified two-port black box model. This model includes small-signal equivalent circuits of components used for 2.5 Gbps DFB laser modules such as DFB laser, coplanar waveguides, matching resistor, bonding wires, and thermoelectric cooler (TEC). From this equivalent circuit modeling, we show that calculated frequency characteristics of DFB lasers on submount and complete DFB laser modules are similar to their measured frequency characteristics, respectively. Based on this equivalent circuit model, we propose and demonstrate a method that can improve frequency characteristics of 2.5 Gbps DFB laser modules through both experiments and simulations.