Monolithic integration of spot-size converters with 1.3-/spl mu/m lasers and 1.55-/spl mu/m polarization insensitive semiconductor optical amplifiers

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-/spl mu/m Fabry-Perot lasers and 1.55-/spl mu/m 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 /spl mu/m) integrated with 1.3-/spl mu/m lasers and 1.55-/spl mu/m SOAs exhibit beam divergences as low as 12/spl deg//spl times/12/spl deg/ and 12/spl deg//spl times/15/spl deg/, 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.