40-Gb/s Operation of a 1.3-/1.55-μm InGaAlAs Electroabsorption Modulator Integrated With DFB Laser in Compact TO-CAN Package

We have developed compact, cost-effective transistor-outline (TO)-CAN modules based on a 1.3-/1.55-μm InGaAlAs electroabsorption modulator integrated with a distributed feedback laser (EML), and realized the 40-Gb/s operation of these modules for the first time. We propose a new method for connecting a straight RF substrate and a TO-CAN stem that minimizes the air gap between them, and that suppresses the impedance mismatch at the connection interface. We also employ a liquid crystal polymer as an RF-line substrate, and apply a borosilicate glass-based coaxial RF pin, which is compatible with K connector glass beads to the TO-CAN stem. By using these modules, we confirm experimentally that the impedance of the entire RF transmission line is approximately 50 Ω throughout the module, and achieve an electrical-to-optical 3-dB-down frequency bandwidth ( f_3dB) of over 33 GHz. We also achieve 40-Gb/s clear eye openings for both 1.3- and 1.55-μm EML-based modules.