Design of compact and efficient polarizationin-sensitive taper coupler for SiGe photonic integration

We have proposed a polarization-insensitive laterally tapered coupler for the integration of the active Ge/ SiGe multi-quantum-well device with a passive SiGe waveguide. A 45-mu m-long taper is designed to achieve more than 90% coupling efficiency for both TE- and TM-polarized modes. The mode interference is utilized to obtain a compact taper coupler with high coupling efficiency. Fabrication tolerances are analyzed in terms of taper width, thickness, material refractive and operation wavelength. The results indicate that a width variation of +/- 200 nm and a thickness variation of +/- 100 nm are allowed. The designed taper coupler can provide efficient coupling under normal operating conditions in the wavelength range of 1460-1625nm. (C) 2016 Optical Society of America