TY - DATA T1 - Data underlying the publication and chapter 3: Breakdown of spin-to-helicity locking at the nanoscale in topological photonic crystal edge states PY - 2023/07/24 AU - Sonakshi Arora AU - Thomas Bauer AU - ReneĢ Barczyk AU - Ewold Verhagen AU - L. (Kobus) Kuipers UR - https://data.4tu.nl/articles/dataset/_/18779327 DO - 10.4121/18779327.v1 KW - Spin density maps KW - dispersion relation KW - SNOM tip KW - silicon-on-insulator waveguide structure KW - topological waveguides N2 -

We measure the local near-field spin in topological edge state waveguides that emulate the quantum spin Hall effect. We reveal a highly structured spin density distribution that is not linked to a unique pseudospin value. From experimental near-field real-space maps and numerical calculations, we confirm that this local structure is essential in understanding the properties of optical edge states and light-matter interactions. The global spin is reduced by a factor of 30 in the near field and, for certain frequencies, flipped compared to the pseudospin measured in the far field. We experimentally reveal the influence of higher-order Bloch harmonics in spin inhomogeneity, leading to a breakdown in the coupling between local helicity and global spin.

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