Correction to: Nature Communications https://doi.org/10.1038/s41467-018-03697-9, published online 11 April 2018

The original PDF version of this Article contained an error in Equation 1. The ‘Λ’ was missing from the denominator, and incorrectly read:

$$n\frac{{2{\mathrm{\pi }}}}{{}} = k_{\mathrm{i}} + k_{\mathrm{d}}\,{\mathrm{sin}}\,(\theta_{\mathrm{d}}).$$

The correct form of Equation 1 is:

$$n\frac{{2{\mathrm{\pi }}}}{\Lambda } = k_{\mathrm{i}} + k_{\mathrm{d}}\,{\mathrm{sin}}\,(\theta_{\mathrm{d}}).$$

This has been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.