High performance modules of 2.5 Gbps modulator integrated DFB lasers usingnew RF impedance matching technique

We report the Improvement of frequency response characteristics of 2.5 Gbps modulator integrated distributed feedback (MI-DFB) laser modules using new impedance matching technique. Frequency responses for the fabricated modul e using the '+' shaped microstrip line for impedance matching have been sig nificantly improved such as the RF return loss of I I dB and the 3 dB frequ ency bandwidth of 4.1 GHz, compared to 6 dB return loss and 1.5 GHz bandwid th for the conventional module. These results can be also well predicted by the simulation of frequency responses for the modules. From the fabricated MI-DFB laser modules, good transmission performance has been obtained up t o 640 km.