Adiabatic Waveguide Taper Profile Optimization on Al2O3/Si Platform for Polarization Insensitive Fiber-to-Chip Light Coupling

Edge couplers are an essential class of fiber-to-chip light couplers. They generally consist of a taper that adiabatically transforms a large fiber mode into a smaller waveguide mode, however, this requires long tapers. Although linear, quadratic, cubic, and exponential taper profiles have been used to design tapers [1] , a more flexible design optimization procedure is desired for shorter tapers at minimal loss. In this work, we use a numerical mode solver (Lumerical MODE), based on eigenmode expansion method, to optimize an Al 2 O 3 /Si inverse taper at 1550 nm wavelength with a particle swarm optimization algorithm. This method is computationally efficient and potentially applicable to all adiabatic waveguide tapers.