Mpolyanskiy

Welcome to Wikipedia. Although everyone is welcome to contribute constructively to the encyclopedia, one or more of the external links you added do not comply with our guidelines for external links and have been removed. Wikipedia is not a collection of links; nor should it be used for advertising or promotion. Since Wikipedia uses nofollow tags, external links do not alter search engine rankings. Note also that adding links to your own site is a conflict of interest, and should be avoided. If you feel the link should be added to the article, please discuss it on the article's talk page before reinserting it. Please take a look at the welcome page to learn more about contributing to this encyclopedia. Thank you.--Srleffler (talk) 04:14, 31 August 2008 (UTC)

Please do not create links to your own websites, even if the sites do not contain advertisements. --Srleffler (talk) 15:59, 31 August 2008 (UTC)

M squared

I reverted you at M squared. It's not obvious, but for a given laser cavity, a higher-order mode with M² > 1 is M times larger in diameter everywhere, compared to the lowest-order (Gaussian) mode of that cavity. The beam gets larger both in near field and far field. If you consider two beams with the same diameter in the far field, you would be correct that the spot would be M² larger in diameter at the waist.

Putting that another way: you are absolutely correct that for a given size input beam, focus size scales as M². If you're considering the output of a given laser cavity, however, when the laser transitions from the lowest-order mode (M = 1) to a mixture of higher-order modes, the collimated beam size increases by M and the waist size also increases by M, so that the beam parameter product scales as M².--Srleffler (talk) 03:24, 11 January 2018 (UTC)