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arXiv · 1904.05513

Complete polarization control for a nanofiber waveguide using directional coupling

Fuchuan Lei·Georgiy Tkachenko·Jonathan M. Ward·Síle Nic Chormaic
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Abstract

Optical nanofiber waveguides are widely used for near-field delivery and measurement of light. Despite their versatility and efficiency, nanofibers have a critical drawback - their inability to maintain light's polarization state on propagation. Here, we design a directional coupler consisting of two crossed nanofibers to probe the polarization state at the waist region. Directionality of coupling occurs due to asymmetric dipolar emission or spin-locking when the evanescent field pattern breaks the mirror symmetry of the crossed-nanofiber system. We demonstrate that, by monitoring the outputs from the directional coupler, two non-orthogonal polarization states can be prepared at the nanofiber waist with a fidelity higher than 99%. Based on these states, we devise a simple and reliable method for complete control of the polarization along a nanofiber waveguide.

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Fuchuan Lei, Georgiy Tkachenko, Jonathan M. Ward, Síle Nic Chormaic. 2019-04-11. Complete polarization control for a nanofiber waveguide using directional coupling. https://doi.org/10.1103/physrevapplied.11.064041

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