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To reduce packaging costs, it is necessary to use passive alignment between the laser diodes and optical fiber. Such an alignment requires low-coupling loss and large positional alignment tolerances. This is achievable with integrated spot-size converters, which permit to match the near field of a laser to that of a flat-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-μm Fabry-Perot lasers and 1.55-μm semiconductor optical amplifiers (SOAs). The spot-size expansion is simulated using a two-dimensional (2-D) beam propagation method analysis. Short spot-size converters (100 μm) integrated with 1.3-μm lasers and 1.55-μm SOAs exhibit beam divergences as low as 12°×12° and 12°×15°, 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