Reconfigurable TE-pass polarizer based on lithium niobate waveguide assisted by Ge₂Sb₂Te₅ and silicon nitride

On-chip polarization management components play a critical role in tackling polarization dependence in the lithium-niobate-on-insulator (LNOI) platform. In this work, we proposed a reconfigurable TE-pass polarizer based on optical phase change material (GST) and the LNOI wafer. The key region is formed by a hybrid GST-S i ₃ N ₄ layer symmetrically deposited atop the centerline of the LNOI waveguide along the propagation direction where the GST is sandwiched in the middle of the S i ₃ N ₄ layer. Whether the polarizer will take effect depends on the phase states of the GST layer and the graphene and aluminum oxide layers are coated atop the G S T-S i ₃ N ₄ layer as the microheater to control the conversion of phase states. The proposed device length is 7.5 µm with an insertion loss (IL)=0.22 dB and extinction ratio (ER)=32.8 dB at the wavelength of 1550 nm. Moreover, it also has a high ER (>25d B) and a low IL (<0.5d B) in the operating bandwidth of 200 nm. Such a high-performance TE-pass polarizer paves a new way for applications of photonics integrated circuits.