Monolithic integration of spot-size converters with 1.3-μm lasers and 1.55-μm polarization insensitive semiconductor optical amplifiers

To reduce packaging costs, it is necessary to use passive alignffment between the laser diodes and optical fiber, Such an alignment requires low-coupling loss and large positional alignment tolerances, This is achievable,vith integrated spot-size converters, which permit to match the near field of a laser to that of a Bat-end single-mode fiber (SMF), In this paper, we first review briefly the different technological approaches to realize spot-size converters. Then, we focus on the double-core structure developed both for 1.3-mu m Fabry-Perot lasers and 1.55-mu m semiconductor optical amplifiers (SOA's), The spot-size expansion is simulated using a two-dimensional (2-D) beam propagation method analysis. Short spot-size converters (100 mu m) integrated with 1.3-mu m lasers and 1.55-mu m SOA's exhibit beam divergences as low as 12 degrees x 12 degrees and 12 degrees x 15 degrees, respectively, The performances of devices with integrated spot-size converters are reported and discussed, A 2-in wafer process is used thanks to the versatility of the double-core structure and its compatibility with buried ridge stripe technology.