An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Tucker-Schwartz JM, Hong T, Colvin DC, Xu Y, Skala MC.Tucker-Schwartz JM, et al.Opt Lett. 2012 Mar 1;37(5):872-4. doi: 10.1364/OL.37.000872.Opt Lett. 2012.PMID: 22378422Free PMC article.