Ultra-compact, efficient and high-polarization-extinction-ratio polarization beam splitters based on photonic anisotropic metamaterials.

Anisotropic metameterials (AM) provide a new avenue for a next-generation silicon platform to design ultra-compact, densely integrated optical components, thus functional devices based on AM are drawing increasing attention recently. Here, we propose a novel efficient polarization beam splitter (PBS) with high polarization extinction ratio based on AM. An ultra-compact coupling region of 2.5 × 14 µm is achieved by tailoring the AM structures, which can efficiently suppress the TE mode coupling, and enhance the TM mode coupling in the directional couplers simultaneously. The insertion loss is simulated to be as low as <0.2 dB within a bandwidth of 70 nm for both modes, and the polarization extinction ratio is as high as 46 dB and 33 dB for TE and TM modes, respectively. We also experimentally demonstrate the proposed PBS, with low insertion loss of 1 dB , high extinction ratio of >20 dB and wide operational bandwidth of >80 nm.