Investigation of the capacitance of integrated DFB-EAMs with shared active layer for 40 GHz bandwidth

Electro absorption modulators (EAM )integrated with distributed feedback (DFB) lasers are attractive light sources for modulation speeds up to 40 Gbps. A model was developed that considers intrinsic carrier phenomena and extrinsic parasitics of a DFB-EAM. With this model, the small signal measurements could be verified and design rules were identified. Simulation results are in excellent agreement with measured data and allow for detailed insight in carrier pile-up and field spreading related effects. By design optimization, the 3 dB bandwidth of the devise was boosted from 18 GHz to 41 GHz.