Hybrid-integration of SOA on silicon photonics platform based on flip-chip bonding

Abstract

A precise flip-chip bonding (FCB) technology for indium phosphide semiconductor optical amplifiers (InP-SOAs) on a silicon photonics platform within less than ±1-μm alignment accuracy was developed. For efficient optical coupling and a relaxed alignment tolerance, the mode field on both the InP-SOAs and the Si waveguides was expanded by spot-size converters (SSCs). On the InP-SOAs, width-tapered SSCs were used to obtain an isotropic mode-field having an approximately a 3-μm diameter. On the silicon photonics platform, dual-core SSCs were used to expand the same mode-field size of 3 μm as for the SSCs on SOAs. Using the FCB technology and the SSCs, an in-line optical amplification of 15 dB was achieved by in-line integrated SOAs with angled waveguides. The optical coupling losses were 7.7 dB, which included 5.1-dB excess losses by misalignment and a gap between InP-SOA and Si waveguides. A 4 × 4 Si switch with a hybrid-integrated 4-ch SOA array was fabricated, and achieved the first demonstration of a lossless Si switch.