Efficient Evanescent-Wave Electro-Optic Tuning on Silicon Nitride-Polymer Hybrid Waveguide

Silicon nitride (SN) is a CMOS-compatible and low-loss dielectric waveguide material, making it ideal for passive waveguides. However, it lacks the electro-optic (EO) effect required for active tuning. Electro-optic activation on SN is crucial for developing tunable photonic integrated circuits. Previous hybrid integration of EO materials on SN either involves complex design and fabrication processes or introduces additional optical loss, posing significant challenges for straightforward and effective EO activation. This manuscript demonstrates a simple evanescent-wave EO hybrid waveguide by integrating electro-optic polymer onto the SN waveguide. We optimize the evanescent field, electro-optic interaction and electric field poling to achieve high-efficiency poling and strong EO interaction. A low half-wave voltage-length products (VπL) of 5.2 V•cm, high EO coefficient of 70 pm/V and a low Vπ of 2.1 V in asymmetric Mach-Zehnder interferometer waveguides have been achieved with negligible additional optical loss. This straightforward and efficient EO activation strategy holds promise for cost-effective active photonic integrated circuits on SN platform.