Entedhar Sarhat : Please stop posting other people's articles and texts which have nothing to do with the posters question (you did not even answer the question regarding wavelength) as your "answers" to dozens and dozens of RG questions. You do not read any of the posts or their responses. You are wasting everyone's time. You do not help any of the people asking for help by replying to these posts.
If you wish to reference an article, then please learn to use a LINK (url) with a proper citation, if you have permission, not copy/paste the text only as your answer.