Electro-optic tunable Bragg grating filters on hybrid silicon and lithium niobate thin films

The hybridization of mono-crystalline silicon and lithium niobate thin films (Si-LNOI) combines the remarkable electrical properties and mature micro-nano processing technologies of Si, as well as the excellent optical properties of LN, which provides a new material platform for integrated photonics. Bragg grating filter implemented by the sidewall modulation of nanowire waveguide could realize filtering function, and was widely used in optical communication systems. In this study, uniform and π-phase-shifted Bragg grating filters were designed, fabricated and characterized on Si-LNOI. For uniform Bragg grating filter, the measured extinction ratio (ER) could be as high as 29 dB. For the π-phase-shifted Bragg grating filter, a high normalized transmittance of 0.50, a high Q factor of 3.4 × 10 4 , and a high ER of 20 dB were achieved. Additionally, effective electro-optic (E-O) modulation with a tuning efficiency of 16 pm/V was realized. This study provides a new solution for the new generation of integrated photonic devices with high density and low energy consumption.