High Efficiency Silicon Edge Coupler Based On Uniform Arrayed Waveguides With Un-Patterned Cladding

In this work, we demonstrate an edge coupler (EC) for the coupling between the single mode fiber (SMF) and the silicon photonic waveguide. High coupling efficiency can be achieved by using arrayed waveguides at 1550 nm with an un-patterned cladding. With such a design, the light will be “pulled” to the top cladding, avoid the using of a cantilever structure. Compared to the conventional inverse taper spot size converter, the widths for the arrayed waveguides are the same, thus it is not critical to determine the position of the end facet for dicing/polishing. We fabricated the proposed structure with only one-step lithography following by a dry etching process. The measured coupling loss is around 1.7 dB/facet, which agrees well with the simulations.