Optical coupling analysis of dual-waveguide structure for monolithic integration of photonic devices

We proposed the dual-waveguide structure (DWS) with spot size converters and demonstrated the monolithic integration of both photodetector (PD) and electroabsorption modulator (EAM) based on the DWS. The coupling loss between the device facet and a lensed fiber was as small as 2.13 dB. The responsivity of PD and the extinction ratio of EAM were 0.58 A/W and 20 dB at -4 V/sub dc/, respectively. From the optical coupling analysis, it was proved that the dual-waveguide scheme provided one of the best solutions for the monolithic integration of optoelectronic devices.