Non-linear spot-size converter coupler for germanium/Si photodetectors

Coupling between monomode silicon waveguides and Ge photodetectors is challenging due to the size mismatch between both components. This work proposes a non-linear tapered coupling device to couple light from a silicon on insulator waveguide to an SOI Ge photodetector. For our 32.1 µm non-linear spot-size converter, the simulated transmission coefficients in the SCL band for 1550 nm, 1460 nm, and 1625 nm wavelength are -0.0113, -0.059, -0.0092 dB, respectively; while state of the art linear spot-size converters of the same transmission coefficients are around 211% bigger.