Optimization of SiN/Polymer Hybrid Electro-Optically Tunable Long-Period Waveguide Grating

Long-period waveguide gratings (LPWGs) are key wavelength-selective components with broad applications in optical communications and sensing. Silicon nitride (SiN) is an attractive platform due to its wide transparency window, low optical loss and CMOS compatibility; however, conventional SiN-based LPWGs lack efficient high-speed tuning mechanisms, which limits their use in dynamically reconfigurable systems. In this work, an electro-optically tunable LPWG based on a SiN/electro-optic polymer (EOP) hybrid structure is proposed and optimized. An intermediate Epocore isolation layer is introduced between the SiN core and the EOP cladding to suppress the electric-field-induced modulation of the core mode. This configuration enables more efficient EO tuning of the effective index difference between the core mode and cladding mode. A systematic parametric optimization is carried out, including waveguide geometry, grating period, and electrode configuration. The simulation results show that the proposed device exhibits a high tuning efficiency of 1.41 nm/V. The proposed design combines compact footprint, CMOS compatibility, and efficient electro-optic tunability, providing a practical approach for reconfigurable integrated photonic filters.