Asymmetric silicon–polymer hybrid waveguide for second-harmonic generation based on modal phase matching

Abstract

We propose and design a nonlinear-polymer-filled asymmetric silicon slot waveguide (SSW) for efficient second-harmonic generation. The distinct modal dispersion of the designed asymmetric SSW is used to achieve phase matching between the zeroth-order waveguide mode at the fundamental frequency ( λ = 3.1 µ m ) and the second-order mode at the second-harmonic frequency ( λ = 1.55 µ m ). Simulation results show a conversion efficiency of P 2 ω / P ω = 32 % with only 10 mW pump power. This high efficiency is a consequence of introducing an asymmetry in the SSW which not only could provide modal phase matching but also preserves high modal overlap between the interacting waves and leads to relatively low propagation loss. The proposed structure, which is well realizable with current CMOS technology, allows extra tuning by the electro-optic effect for eliminating phase mismatch resulting from fabrication errors.