Bandwidth Extension of EML Chip-on-Carrier Submodule Using Precise Parameters Extraction

The electro-absorption modulated laser (EML) chip-on-carrier (COC) submodule has a complex equivalent circuit model, making it challenging to characterize the EML parameters directly. An efficient theoretical model is presented which closely approximates the actual situation by combining the conventional EML COC equivalent circuit model with the RF response characteristics of the chip carrier. Compared with the conventional model, the proposed method can help quickly find the optimal length of the bonding wires and improve the modulation bandwidth. The accuracy of the simulation model for the optimal bonding wire length is verified by experiment. By non-linear numerical fitting of the model to the measured frequency response of the EML submodule, the intrinsic parameters of EML chip are precisely extracted. As a result, the 3-dB bandwidth of the EML COC submodule is increased from 43.5 GHz to 53.4 GHz, and clear transmission eye pattern of 53-Gbaud PAM-4 signal is also achieved.