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Title: Ultra-high extinction ratio polarization beam splitter with extreme skin-depth waveguide

In this Letter, we present a high extinction ratio and compact on-chip polarization beam splitter (PBS), based on an extreme skin-depth (eskid) waveguide. Subwavelength-scale gratings form an effectively anisotropic metamaterial cladding and introduce a large birefringence. The anisotropic dielectric perturbation of the metamaterial cladding suppresses the TE polarization extinction via exceptional coupling, while the large birefringence efficiently cross-couples the TM mode, thus reducing the coupling length. We demonstrated the eskid-PBS on a silicon-on-insulator platform and achieved an ultra-high extinction ratio PBS (≈<#comment/>60dBfor TE and≈<#comment/>48dBfor TM) with a compact coupling length (≈<#comment/>14.5µ<#comment/>m). The insertion loss is also negligible (<<#comment/>0.6dB). The bandwidth is><#comment/>80(30) nm for the TE (TM) extinction ratio><#comment/>20dB. Our ultra-high extinction ratio PBS is crucial in implementing efficient polarization diversity circuits, especially where a high degree of polarization distinguishability is necessary, such as photonic quantum information processing.

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Optics Letters
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Article No. 2164
0146-9592; OPLEDP
Optical Society of America
Sponsoring Org:
National Science Foundation
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