Making negative refraction with positive index material

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Discussion Overview

The discussion revolves around the possibility of achieving negative refraction using positive index materials, such as glass, rather than relying solely on metamaterials. Participants explore theoretical implications, practical applications, and the nature of materials involved in this phenomenon.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that metamaterials are necessary for achieving negative refraction, while others question whether positive index materials can be oriented to achieve similar effects.
  • One participant mentions "anomalous dispersion," where permittivity is positive but decreases with frequency, complicating practical applications due to high absorption.
  • There is a discussion about the geometry of metamaterials, with one participant noting that the arrangement of components like rods and split rings contributes to their left-handed properties.
  • Another participant proposes that if materials can be oriented correctly, it might be possible to mimic negative refraction without creating metamaterials.
  • Concerns are raised about the feasibility and understanding of the proposed ideas, with some participants expressing frustration over perceived lack of clarity in the questions being asked.
  • One participant emphasizes the need for actual proof of concepts being discussed, suggesting a desire for empirical validation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether negative refraction can be achieved with positive index materials. There are multiple competing views, with some advocating for the necessity of metamaterials and others exploring the potential of positive index materials.

Contextual Notes

Participants express uncertainty regarding the definitions and properties of materials involved, particularly in relation to metamaterials and their geometrical configurations. There are unresolved questions about the practical applications and theoretical underpinnings of the proposed ideas.

St. Aegis
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I was thinking about and I think it might be possible, but before I do anything stupid, anything have an opinion about this?
 
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Are you referring to metamaterials?
 
positive index material is any material that is not meta-material
like glass, meaning index n>1
 
St. Aegis said:
positive index material is any material that is not meta-material
like glass, meaning index n>1

Er.. technically, the rods and split rings that make up the metamaterial ARE positive index material! It is how the geometry of the various components of the metamaterial that causes it to have the left-handed property.

There are others, such as layered semiconductors:

http://physicsworld.com/cws/article/news/31554;jsessionid=412475B70D3407BA28ADCE13778A3672

The only "natural" material that I know of is a ferromagnet that was reported recently:

A. Pimenov et al. Phys. Rev. Lett. 98, 197401 (2007);
http://physicsworld.com/cws/article/news/30020 (free registration required).

But I'm not sure if this is the "positive index material" that you're looking for, which, as I've described above, is rather strange, since the metamaterial and layered semiconductors are made up of positive index material.

Zz.
 
It is called "anomalous dispersion" the permittivity is positive and can be greater than one, but it decreases with increasing frequency. It usually occurs near a resonance of the material, and is difficult to use because the absorption is very high there.
 
They are calling these 'metamaterials'. Originally negative index of refraction was demonstrated in the microwave region. The push is on to develop materials toward the visible range of the spectrum. As clem indicates, as developed, they are frequency selective. Wikipedia has an article on metamaterials.
 
well yes i know that all matter, except metamaterials exhibit this, but I was thinking, for like things like glass, it is definitely impossible right?
 
St. Aegis said:
well yes i know that all matter, except metamaterials exhibit this, but I was thinking, for like things like glass, it is definitely impossible right?

The fact that you already know that glass has a positive index of refraction makes the question puzzling. I'm guessing you don't intend to use glass to construct either layered or a metamaterial.

Zz.
 
I swear, when I posted #6 only the initial post and Clem's were visible... What gives?
 
  • #10
The op made 2 identical threads, which is a no-no on PF. Since both already had responses, I merged both of them into one.

Zz.
 
  • #11
couldnt you orient some materials such that negative refraction occurs?
 
  • #12
ZapperZ said:
The op made 2 identical threads, which is a no-no on PF. Since both already had responses, I merged both of them into one.

Zz.

Thanks, Zapper
 
  • #13
St. Aegis said:
couldnt you orient some materials such that negative refraction occurs?

Assuming that you're still stuck with "glass" or other positive index material, then isn't this what is done with the metamaterial in the first place? I mean, look at the orientation of the rods and split rings, for example, with respect to the orientation of the E and B fields of the EM radiation.

This is getting puzzling all the time, because it appears that you are aware of the development in this field, but then you continue to ask things that, to me, are rather obvious. Can you tell me what it is that you're looking for that is not satisfied by the metamaterial? I can tell you right off the bat that so far, the characteristics that you're asking (material with positive index, having a certain orientation) fit with the metamaterial. So why isn't that sufficient? How about being a bit more verbose in your question and what exactly you're trying to get at, rather than just a one-line response? What I've typed here in this post alone is more than what you've typed in all of your posts in this thread combined, and frankly, I'm getting tired of putting all this one-sided effort.

Zz.
 
  • #14
no no no,
imagine, that you have slabs of material right? Now light strikes one material, but let's say that this material is tilted in one direction, such that when light strikes this medium, what occurs is that light will bend (let us assume the second material's index is much higher than the original material). Right? This means that light can be directed in the same direction of negative refraction when light is shone through. I find this quite awkward I do not mean just electromagnets and everything, I mean the actual meta-materials. I find it awkward that this effect can be mimicked. Now say that you can use this in application; then we won't have to create meta-materials but rather know how to arrange positive refraction material to bend light in that manner. Do you see where I am going with this?
 
  • #15
bump?
 
  • #16
St. Aegis said:
no no no,
imagine, that you have slabs of material right? Now light strikes one material, but let's say that this material is tilted in one direction, such that when light strikes this medium, what occurs is that light will bend (let us assume the second material's index is much higher than the original material). Right? This means that light can be directed in the same direction of negative refraction when light is shone through. I find this quite awkward I do not mean just electromagnets and everything, I mean the actual meta-materials. I find it awkward that this effect can be mimicked. Now say that you can use this in application; then we won't have to create meta-materials but rather know how to arrange positive refraction material to bend light in that manner. Do you see where I am going with this?

Nope. This makes no sense.

Besides, do you think physicists and engineers are that dumb to not even think or attempted such a thing, especially when they could come up these matematerial?

Zz.
 
  • #17
well besides considering that physicists should explore everything around them, I say why not and be that dumb. Hell, people spend government money playing around with computer programs, I don't see why not.
Besides, what I am looking for is actual proof.
 

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