Reconfigurable on-chip polarizers enabled by phase-change-material-mediated loss engineering

Active on-chip polarization control is essential for integrated photonic systems. Here, we propose reconfigurable on-chip polarizers based on a nonvolatile phase-change-material-assisted symmetric three-waveguide directional coupler. By exploiting the distinct coupling behaviors of TE and TM modes through controlled phase mismatch, the propagation path and attenuation of different polarizations can be independently engineered. Specifically, a TE-pass polarizer is realized by using Ge 2 Sb 2 Te 5 (GST) as a phase-matching and loss-control medium on the side waveguides, while a TM-pass polarizer is achieved by introducing a resonant GST-loaded section in the central waveguide that selectively suppresses the TE mode with a high extinction ratio. The proposed polarizers demonstrate broadband operation from 1500 nm to 1600 nm, with polarization extinction ratios over 20 dB for both configurations. This work provides a compact, reconfigurable, and nonvolatile strategy for high-contrast polarization control in silicon photonic integrated circuits.