Scientific Reports 6: Article number: 24592; Published online: 19 April 2016; Updated: 02 June 2016

The Acknowledgements section in this Article is incomplete.

“The authors gratefully acknowledge Raffaele Colombelli for precious suggestions and insights on the application of coupled-mode models to strongly-coupled systems”.

should read:

“The authors gratefully acknowledge Raffaele Colombelli for precious suggestions and insights on the application of coupled-mode models to strongly-coupled systems. This work was in part supported by the European Research Council through the Advanced Grant SOULMAN (ERC-FP7-321122)”.