Talk:Evanescent field

message: Could someone please add references to the electric section?  Sorry - I don't know how to tag it as needing references. 137.215.6.53 (talk) 07:40, 18 July 2008 (UTC)
thread_title:  References 

message: Isn't this page lacking the information (or at least needing to put it more clearly) that the direction of the evanescent electric field is the same of the exponential decaying? I have the impression sometimes that people care much about the fact that the evanescent waves "evanesce" exponentially, but this is by no means its most notable characteristic. The fact that the field is in the same direction of this decay is the one worth noting. -- NIC1138 (talk) 05:18, 13 January 2009 (UTC)
replies: text: Correct me if I'm wrong. My understanding of evanescent waves is that they are already by nature "directional." It would follow that the exponential decay is also directional. Pointing it out, seems to me to be akin to saying "The sky is blue, but it is not black." The last half of the sentence is unnecessary. Simple logic should lead the reader to infer the decay is in the same direction IMHO. --24.63.66.140 (talk) 16:53, 28 August 2009 (UTC)
thread_title:  direction of evanescence 

message: I found this article while preparing an exam in photonics and I think a correction might be necessary.
My understanding is that an evanescent wave appears when a wave crosses from a denser to a thinner material, in my case optically denser/thinner. This is one of the prerequisites for total reflection, which is connected to the appearance of evanescent waves.
Is this true for any electromagnetic wave? Everything I've read seems to imply so, however I'm rather a layman in the field so I'd like to be sure :)
Longbowman3 (talk) 13:57, 16 April 2009 (UTC)
thread_title:  Possible addition/correction 

message: Can I take it that "with an intensity that exhibits exponential decay with distance" means "of an intensity which diminishes exponentially with distance"?  Or is something subtler being implied here, something to do with "exhibit" or "decay"? Unfree (talk) 04:56, 7 March 2010 (UTC)
thread_title: Exhibit

message: I find "Evanescent waves are a general property of wave-equations" confusing.  Surely, an equation is something a human being can write down in pencil on paper.  Surely, evanescent waves must be physical phenomena.  Surely, "property" and "general property" must have quite well established meanings in science.  Can it be said that evanescent waves are phenomena which can be seen to emerge naturally from the wave equations, are implicit in them, or can be accounted for by them? Unfree (talk) 05:19, 7 March 2010 (UTC)
replies: text: How about "Evanescent waves are one general form of solution to wave equations"? It's referring to the fact that, depending on coordinate system, spatial functions of the forms exp(-az), exp(-j*az), and Bessel/Neumann/Hankel functions (among others) are all permissible solutions to the general wave equation, not specific to Maxwell's equations. 03:52, 16 March 2010 (UTC)
thread_title: Phenomena

message: Considering the direction of movement and the surface of the medium, one would naturally expect the incident angle of the photon, phonon, or whatever, to refer to the angle between the two, rather than between the photon and the normal to the surface.  So "they strike it at an angle greater than the so-called critical angle" would seem to imply less shallow rather than shallower.  A rewording is called for, or at least a clarification.  (Also, how is "so-called" called for?) Unfree (talk) 05:31, 7 March 2010 (UTC)
thread_title: Incident angle

message: "EM waves", I take it, is an abbreviation for electromagnetic waves?  If so, let's insert "(EM)" after the first occurrence of "electromagnetic", or even better, spell it out each time. Unfree (talk) 05:38, 7 March 2010 (UTC)
thread_title: EM

message: Just a hunch, but thinking about "in the nearfield region within one-third wavelength" makes me wonder whether this might be two ways of saying the same thing.  Is it?  If so, let's state so explicitly and eliminate a layer of logical abstraction. Unfree (talk) 05:44, 7 March 2010 (UTC)
thread_title: The "nearfield" region

message: The way "in quantum mechanics" enters the discussion suggests (considering quantum mechanics to be valid) that all that has gone before is phony.  It's as if we weren't discussing the real world, but an erroneous, prehistoric notion of it.  I'm sure this is a familiar situation to those who learn Maxwell's equations before Schroedinger's, and being unfamiliar with any of them, I'm out of my league here, but an introductory sentence or two ought to suffice to explain why quantum mechanics is unnecessary at the outset, but ought to crop up later. Unfree (talk) 06:08, 7 March 2010 (UTC)
thread_title: Quantum mechanics

message: Explaining "the unit vector in the z direction" crops up a little late, after we've been exposed to the unit vectors in the x and y directions without any explanation.  Also, we're told that alpha is a real number, which, when multiplied by i, gives an imaginary result.  That's clear.  But it isn't clear at the outset (especially without understanding the unit vector notation) exactly what the "components" are, and what alpha and beta are. Unfree (talk) 06:19, 7 March 2010 (UTC)
thread_title: Unit vector notation

message: The caption of the pictures of the refracted versus evanescent wave in the "Total internal reflection of light" section incorrectly called the refracted wave the "diffracted wave." I fixed this and also removed a link in that caption to Diffraction limit because I didn't see how it was relevant (admittedly that page does talk about evanescent waves being used to beat the diffraction limit in imaging, but that didn't seem relevant to the picture). If I am wrong in these things, please revert. 165.124.205.144 (talk) 08:13, 27 May 2010 (UTC)
replies: text: It appears to me that your edit is correct. The caption now reads: Representation of a refracted incident wave and an evanescent wave at an interface. I don't see where diffraction would be invloved in these two images. It seems obvious the wave is "refracting" in the top picture. Thanks for your correction. ----Steve Quinn (formerly Ti-30X) (talk) 18:00, 27 May 2010 (UTC)
thread_title:  Diffraction? 

message: The history of the discovery should be mentioned. I think two men discovered the wave at about the same time.  — Preceding unsigned comment added by 92.27.109.117 (talk) 15:37, 26 February 2013 (UTC)
thread_title:  History 

message: In a standing wave, the nodes don't move.  However, in the case of total internal reflection, the nodes move in a direction that is parallel to the reflecting surface.Constant314 (talk) 18:01, 8 April 2013 (UTC)
replies: text: That's not exactly true. You're thinking of a fully standing wave which happens when a wave (on a transmission line or a plane wave in space) is fully reflected. When the reflection is partial there is incomplete cancellation and the field has a general "motion" in the direction of the stronger component. Also, even with perfect reflection of a plane wave at an angle, you get "motion" of the standing wave in the transverse direction. I'm not sure why this is important though. Interferometrist (talk) 18:01, 17 October 2015 (UTC)
thread_title:  An evanescent field is not a standing wave. 

message: Sorry to point this out and cause consternation. But an evanescent field is not a wave, for instance according to the definition of wave in Wikipedia. A wave travels in space (or a medium) unless and until it is attenuated or deflected, and carries energy away from the source. By definition an evanescent field does neither. Yes I know that "evanescent wave" is a common expression, and I hear it more than "field" where I work from people who understand what I am saying but don't care about semantics (I've even caught myself saying it!). There is already a redirect page from "evanescent field" to this one. My suggestion would be to reverse them!
Also, on a different subject: a standing wave is not a "wave" either. It is two waves. What is "standing" is the oscillation of the electric (or magnetic) field. Another misnomer but not one that causes confusion.
Evanescent wave is a confusing term because it sounds like something exotic. Actually evanescent fields are ubiquitous, and most electric and magnetic fields in everyday life fall in this category. In your house you are surrounded by 50 (or 60) Hz fields very little of which is radiated into space. It is only when you are very far from all currents (many wavelengths away) that fields are dominated by traveling waves (since, again by definition, any evanescent fields have greatly decayed, whether exponentially or otherwise). Interferometrist (talk) 18:39, 17 October 2015 (UTC)
replies: text: I looked in an older IEEE Dictionary and found "evanescent field" and "evanescent mode" but not "evanescent wave".  If you want to change the name of this article to "evanescent field", I would support the change.Constant314 (talk) 13:22, 18 October 2015 (UTC)
replies: text: Alright I would be so inclined, but will wait a few days to see if anyone else wants to weigh in. Also, I'm not sure how to do this. There is a page for each name, one a redirect. Should I move the content from one to the other? Or delete the current redirect and MOVE this page to the new name? Interferometrist (talk) 10:21, 20 October 2015 (UTC)
replies: text: Probably better ask for help.  I'm sure that moving the content is not the way to go because it loses the history log.Constant314 (talk) 11:41, 20 October 2015 (UTC)

text: I submitted a request to move the page to Evanescent field. Constant314 (talk) 18:57, 24 October 2015 (UTC)

text: The article has been renamed.  There are many instances of wave that need to be addressed. Constant314 (talk) 14:14, 25 October 2015 (UTC)
replies: text: Hi, sorry I've been ill and not attending to this. But yes, the article is a mess now if you focus on the linguistics. However it's the content that is important. I expected that in the first sentence it would point out the common usage of the other term (whether identifying it as a misnomer or not) so that someone recognizes it as a synonym when read elsewhere as well as in the article if those references persist. Or you could do a quick search and replace throughout the article. If I have the energy I will edit the whole lede because I think it has additional errors. Thanks for taking care of the technical task. Interferometrist (talk) 13:58, 26 October 2015 (UTC)
replies: text: Please edit boldly.  My editing takes place mainly on the weekend so we are unlikely to interfere with each other.  I don't think that simply replacing wave with field everywhere is a good idea.  The connotations of the two words are different.  Also, I think clearly that some sources do use evanescent wave so, I think that we should replace wave with field for consistency within the article, but we should avoid depreciating that term evanescent wave.  I hope that makes sense. Constant314 (talk) 14:08, 26 October 2015 (UTC)
thread_title:  "Evanescent wave" a misnomer 

message: When the second object is introduced into the evanescent field of the first object the field stops being evanescent.  The field reflects off the second object, re-reflects off the first object, etc.  The field between the objects must become non-evanescent or there will no power flow.  Evanescent-wave coupling means there is coupling where an evanescent field would exist if the object being coupled were not there.Constant314 (talk) 22:42, 27 October 2015 (UTC)
replies: text: You are absolutely right, and if you want to be very exact with your terminology then this term is self-contradictory and shouldn't be used. But an important point is that "evanescent field/wave" is already a rather inexact term thrown around loosely in different contexts so this usage isn't surprising, and in fact is so common that the name can't be changed. In a similar context, I regularly hear about plane waves at an interface beyond the critical angle being "evanescent waves" even when they excite a nearby atom/conductor/surface such as in FTIR, also called "tunneling" of photons according to quantum concepts. Again, if they actually carry power they are no longer evanescent and when I point this out people agree, shrug their shoulders, and keep on talking that way the next day. I would boldly call these uses a "misnomer" in the article except that someone will (and should!) demand a RS saying so. Interferometrist (talk) 14:37, 28 October 2015 (UTC)
thread_title:  Evanescent-wave coupling, missing important detail 

message: There seems to be excessive hand wringing over whether an evanescent wave is a wave.  The article is about evanescent fields.  I propose that we change all instances in the article to evanescent field (except in direct quotes) an give the alternate names one time in the lede. Constant314 (talk) 22:15, 15 January 2019 (UTC)
replies: text: I totally agree with that. Henri BONDAR (talk) 08:35, 16 January 2019 (UTC)
thread_title:  Modes, fields and waves 

message: In the introduction section, a definition of evanescent field is presented. In the literature, it is presented a novel methodology to analyse this type of waves, regarding its excitation and its propagation. I think it is important to add a simply description about this in this introduction. I suggested the following:
A novel methodology to analyse the excitation and propagation of this type of waves is proposed in , based on geometry. 
:Wikipedia doesn't publish novel methodology.  It may be exciting, but for Wikipedia, we wait until it percolates up to reliable secondary sources, like text books. Constant314 (talk) 20:24, 10 May 2023 (UTC)
thread_title:  Introduction's Suggestion - Update to state-of-the-art information