What is an evanescent wave? What are its applications?

[ksmith1281]

I am reading some papers that mention evanescent waves. From what I can find, evanescent waves occur because of the Maxwell Boundary Conditions but I don't really see how. Could some please comment on this or just on the general topic. Thanks!

 

[y33t]

I am reading some papers that mention evanescent waves. From what I can find, evanescent waves occur because of the Maxwell Boundary Conditions but I don't really see how. Could some please comment on this or just on the general topic. Thanks!

That's a nice question. Evanescent fields are near field effects which are not easy to deal with. We had struggled to derive evanescent fields from Maxwell Equations to solve a problem in an hypothetical fiber network a while ago and I assure you it's not an easy task to mathematically immerse into evanescent phenomena. For general information and some of the applications ; http://www.faculty.iu-bremen.de/dknipp/c320352/Projects/Presentations%202005/CL%20Evanescent%20Fields.pdf

I would like to hear if someone comes up with the proof that derives evanescent fields from Maxwell equations step-by-step.

 

[ksmith1281]

Thanks!

 

[vanhees71]

For those who understand German, here I've written a quite complete review about fields in wave guides (in vacuo):

http://theory.gsi.de/~vanhees/faq/causality/node8.html