Coupler for Butt-Coupling Between Edge-Emitting Lasers and Inverted Si Taper Waveguide

A novel design and analysis of a butt-coupler are presented to be coupled with an edge-emitting laser and a silicon waveguide. The coupler is fairly effective when used with an edge-emitting laser of a certain integrated size and a high refractive index core material. Butt-coupling is not sensitive to polarization as both TE and TM modes achieve similar efficiency. The laser alignment tolerance and silicon waveguide gap in both lateral and vertical positions were studied. Although the air gap between the laser and the silicon cladding reduces coupling efficiency greatly, gap filling can help solve this problem. This design is proved to be quite effective in dealing with high index contrast and huge size mismatch between the laser and semiconductor waveguide.