Broadband Packaging of Photodetectors for 100 Gb/s Ethernet Applications

The packing structure of functional modules is a major limitation in achieving a desired performance for 100 Gb/s ethernet applications. This paper presents a methodology of developing advanced packaging of photodetectors (PDs) for highspeed data transmission applications by using 3-D electromagnetic (EM) simulations. A simplified model of the PD module is first used to analyze and optimize packaging structures and propose an optimal packaging design based on the simplified model. Although a PD module with improved performance proved the success of the optimal packaging design, the simplified model could not identify other important bandwidth limitation effects. Therefore, a full 3-D EM model of PD modules is developed to predict the optical-to-electrical response of the module, and with this model, it is possible to identify a critical mode mismatch effect as another important factor of limiting the bandwidth of PD modules. After eliminating the mode mismatch effect by improving the chip-conductor-backed coplanar waveguide transition, a final optimal packaging structure is implemented for the PD module with reduced attenuation up to 100 GHz and a broader 3-dB bandwidth of more than 90 GHz. Furthermore, the PD module exhibits excellent performance under the high-speed data-transmission experiment with 107 Gb/s data rate.