A large misalignment tolerance multi-branch waveguide for high efficiency coupling

Abstract

Abstract In this paper, a silicon optical waveguide with high light coupling efficiency and large misalignment tolerance between the silicon waveguide and the laser diode is presented. The silicon optical passive device is designed as a multi-branch structure based upon the silicon on insulator (SOI) platform, which is like a power splitter used in turn. The laser diode is mounted at the end of the multi-branch SOI waveguide structure by flip-chip bonding process. Theoretically, by optimizing the silicon waveguide structure, more than 52% light power of the semiconductor laser diode is coupled into the multi-branch waveguide and a mismatch of 20 μ m in a specific direction only leads to a decrease of 5% in the coupling efficiency. Experimentally, a 37.5% coupling efficiency is obtained from an integrated unit consisting of a single mode laser and the multi-branch waveguide by using a normal precision flip-chip bonder. The special multi-branch waveguide structure is reported for the first time.