Polymer micro-ring modulator on silicon nitride platform

The development of silicon nitride (SiN) waveguide platforms has enabled the realization of photonic circuits with unprecedented performance. Despite the exciting progress, SiN suffers from intrinsic material properties that block it for high-speed electro-optic (EO) modulators. Here, we present an approach to heterogeneously integrate organic EO polymer on SiN for high-performance modulators. We utilize the high resistivity of SiN to achieving a strong overlap between the optical and electrical field. Furthermore, sol-gel SiO2 side-claddings inserted in waveguides shorten the inter-electrode distance and increase the EO activity to a much higher level. As a result, the fabricated micro-ring modulator exhibits an electrical tunability of 10 pm/V, corresponding to an in-device EO coefficient as 60 pm/V. High frequency tests in the device show a 3-dB bandwidth of 32 GHz and a data rate of 40 Gbps. The proposed approach will enable efficient mass-production of the micro-footprint modulators and promote the development of integrated SiN photonics.