Electrically tunable momentum space polarization singularities in liquid crystal microcavities

TL;DR

This paper demonstrates that momentum space polarization singularities can be electrically tuned in a liquid crystal microcavity, enabling dynamic control of topological photonic features for potential spinoptronic applications.

Contribution

It introduces a novel method to generate and tune polarization singularities in momentum space using a birefringent liquid crystal microcavity, contrasting with previous static patterning approaches.

Findings

Polarization singularities can be electrically tuned in the microcavity.

Results align with theoretical predictions.

Potential for integration into spinoptronic devices.

Abstract

Momentum space polarization singularities of light appear as vectorial twists in the scattered and radiated far field patterns of exotic photonic structures. They relate to important concepts such as bound states in the continuum, spatiotemporal light steering, polarization M\"obius strips, Berry curvature and associated topological photonic phenomena. Polarization singularities, such as completely circularly polarized C-points, are readily designed in real space through interference of differently polarized beams. In momentum space, they require instead sophisticated patterning of photonic crystal slabs of reduced symmetries in order to appear in the corresponding band structure with scarce in-situ tunability. Here, we show that momentum space singularities can be generated and, importantly, electrically tuned in the band structure of a highly birefringent planar liquid crystal microcavity that retains many symmetries. Our results agree with theoretical predictions and offer exciting possibilities for integration of momentum space polarization singularities in spinoptronic technologies.