Electro-optic tunable optical filter based on long-period waveguide grating in lithium niobate on insulator with absorption ribbons

We propose an electro-optic tunable optical filter based on sidewall long period waveguide grating (LPWG) in lithium niobate on insolator (LNOI). The operation of our proposed filter is based on the mode coupling, filtering, and absorption achieved, respectively, with two corrugated sidewall LPWGs, a tapered waveguide, and two metal ribbons. Our typical fabricated devices achieved a 16.32-dB rejection band and an EO tuning efficiency of ∼0.344 nm/V. Our proposed LPWG and filter are compact and could be integrated with other LNOI waveguide devices to realize more sophisticated functions for on-chip optical signal processing.