Ultrabroadband Polarization Beam Splitter by Harnessing the Dispersion of Subwavelength Metamaterials

The polarization beam splitter (PBS) is a fundamental building block for polarization handling in photonic integrated circuits. The emerging applications in sensing, imaging, and communications demand devices with ultrabroad optical bandwidth. Here, we propose and experimentally demonstrate an ultrabroadband PBS on the 340‐nm silicon on insulator (SOI) platform enabled by dispersion‐engineered anisotropic subwavelength‐grating (SWG) metamaterials. By tailoring the pitch of SWG <100> structures toward the Bragg regime, the coupling‐length dispersion of the PBS for TE polarization is effectively flattened. Measured results show insertion losses are < 1 dB for TE and < 0.6 dB for TM polarization, with an extinction ratio > 17.5 dB for TE and 21 dB for TM across the entire optical communication band (1.26–1.675 µm).