Talk:Optical cavity

Outline at end of practical resonators section
The dot points at the end of the resonators section are vague and confusing and should probably be removed. Lattetime 02:41, 8 February 2007 (UTC)


 * Arnero added that a few days ago. He often adds new content to articles in outline form. Sometimes he comes back and fleshes it out. Sometimes others expand it. Still, outlines within articles are not generally recommended. I've moved it below for discussion and editing. Feel free to edit or comment on it. If it gets expanded to a form suitable for the article, we can move it back in.--Srleffler 05:06, 8 February 2007 (UTC)

Mechanically stable resonators employ massive mechanics:
 * fibers
 * massive aluminum block with small holes for the beam
 * resonator totally with in the laser crystal
 * resonator made of components bonded together

The resonator is kept compact (otherwise massive mechanics would be heavy):
 * fiber in laid out in a coil
 * folded cavity

Also the beam diameter is kept as small as possible:
 * fiber
 * all mirrors in a folded cavity are concave

FSR and Finesse
I think it would be nice if a little was included about the free spectral range, finesse, resonance linewidth and the basic equations used to calculate each of them. For example what is the FSR of each of the types mentioned (confocal, hemispherical, etc.)? Some are c/4L, some c/2L or c/8L. I think a brief explanation of this would be meaningful and helpful. Argentum2f (talk) 16:18, 26 July 2011 (UTC)

Missing words?
In the confocal cavity a ray, which is deviated from its original direction in the middle between the of the cavity, is maximally (compared to other cavities) displaced on the return to the middle. I need to know what, and how must I interpret "maximally"? Maximal in the "right' direction? :-(( 84.197.178.75 (talk) 20:57, 4 March 2012 (UTC)
 * No words have been deleted (I checked). The editor who wrote that, five years ago, is very knowledgeable, but English is not his first language.
 * I think what he is saying is that if a ray is deviated (e.g. by scattering) in the middle of the cavity, the path followed by that ray differs from the path it would have followed by a larger amount than in any other cavity design. I do not know if this is true, and would recommend you verify it before relying on it. The confocal cavity is only marginally stable, though, as indicated by its position on the edge of the blue region of the graph. It's not surprising therefore that it is easy for rays to "walk off" from the mode.--Srleffler (talk) 04:59, 6 March 2012 (UTC)

No mirrors
I think the first sentence is not accurate at all. There are many optical cavities without mirrors. Micro toroids, micro spheres and in general all the micro-resonators does not use mirrors, the Total internal reflection is the mirror like effect but is not a mirror.


 * Please sign and time stamp comments so others can seen where and who is raising concerns. It helps to see the chronology of talking points and who's raising/following up what.


 * Not sure you're right on the mirror thing. Optical resonators in general need not have cavities.  But the article is specifically about 'Optical cavities' which implies an empty space in which modes are confined.  The choice of reflecting surface curvature and spacing is extremely important to understanding what eigenmodes are supported: all of these reflecting surfaces are mirror like in their qualities (they have a radius of curvature and an interface).  It is true that micro toroids, spheres etc have resonant modes and do not have mirrors, but these devices fall more into the broader category of optical resonators.  They are distinctly different from the cavity, in that, their spacial modal confinement is imposed over their entire length of the beam's propagation path. Cavities by contrast reshape the beam at discreet points (i.e. mirrors) and are then allowed to evolve until they hit the next mirror. Cavity implies that there is a vacant space (or at least a medium of constant refractive index) in which the spacial modes evolve freely. --Fincle (talk) 01:42, 21 September 2015 (UTC)

Traveling wave cavities missing?
Optical cavities in practice need not have a standing wave, many lasers, mode cleaning resonators, OPO etc are in a traveling wave design with more than two mirrors. The article is well written, but seems to be blind to the fact that in practice other cavity geometries (other than two mirror linear cavities) are often used as 'cavities'. Explaining how these cavities may be stable and how breaking the returning path degeneracy changes eigenmodes requires a little more detail. --Fincle (talk) 01:25, 21 September 2015 (UTC)

Assessment comment
Substituted at 01:55, 30 April 2016 (UTC)

credit for spherical cavities section
I'm not sure why the sentence about Richard K. Chang is what it is. I've read the collection of relevant papers, most of them have Judith B. Snow as the first author and Richard K. Chang as the third. The one I'm linking (https://www.osapublishing.org/ol/abstract.cfm?uri=ol-10-1-37) is an example, mentions droplets as optical resonators in the abstract, and was published in 1985. --Rk4ds (talk) 00:08, 8 February 2021 (UTC)Rk4ds
 * Just a guess, but Snow might be a grad student and Chang the supervisor. If there were just one paper, I'd say we should credit the lead author. If there are multiple papers from that research group with different credits, we really ought to have a secondary source we can cite, to decide who to credit. Or just credit "researchers at Yale".--Srleffler (talk) 02:37, 8 February 2021 (UTC)