A 25 Gbit/s Transmitter Optical Sub-Assembly Package Employing Cost-Effective TO-CAN Materials and Processes

A cost-effective 25 Gbit/s directly modulated transmitter optical sub-assembly (TOSA) employing transistor outline (TO)-CAN materials and processes is demonstrated. A high speed distributed feedback laser diode (DFB LD) chip used in the TOSA is characterized by a directly high frequency probing measurement and an equivalent circuit model according to the measurement result. Using a TOSA package with TO-CAN structure and applying the deduced equivalent circuit model of the DFB LD chip in the simulation, a modified TOSA is proposed. The parasitic effect of bonding-wire and the gap induced in die bonding process is studied comprehensively to achieve an optimum configuration. Based on the simulated result, the proposed TOSA is fabricated through a conventional TO-CAN and TOSA fabrication process. The measured results show that the TOSA exhibits a 3-dB bandwidth of 18.7 GHz and a clearly opening eye diagram of 25 Gbit/s. This developed TOSA is potential for use in the next generation fiber network of 25 Gbit/s or 100 Gbit/s due to advantages of cost-effective design and mass production capability.