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Making negative refraction with positive index material

  1. Nov 16, 2008 #1
    I was thinking about and I think it might be possible, but before I do anything stupid, anything have an opinion about this?
     
  2. jcsd
  3. Nov 16, 2008 #2

    f95toli

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    Are you refering to metamaterials?
     
  4. Nov 16, 2008 #3
    positive index material is any material that is not meta-material
    like glass, meaning index n>1
     
  5. Nov 17, 2008 #4

    ZapperZ

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    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.
     
  6. Nov 17, 2008 #5

    clem

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    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.
     
  7. Nov 17, 2008 #6
    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.
     
  8. Nov 18, 2008 #7
    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?
     
  9. Nov 18, 2008 #8

    ZapperZ

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    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.
     
  10. Nov 18, 2008 #9
    I swear, when I posted #6 only the initial post and Clem's were visible... What gives?
     
  11. Nov 18, 2008 #10

    ZapperZ

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    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.
     
  12. Nov 19, 2008 #11
    couldnt you orient some materials such that negative refraction occurs?
     
  13. Nov 19, 2008 #12
    Thanks, Zapper
     
  14. Nov 19, 2008 #13

    ZapperZ

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    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.
     
  15. Nov 23, 2008 #14
    no no no,
    imagine, that you have slabs of material right? Now light strikes one material, but lets 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 wont 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?
     
  16. Nov 28, 2008 #15
  17. Nov 28, 2008 #16

    ZapperZ

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    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.
     
  18. Dec 2, 2008 #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 dont see why not.
    Besides, what I am looking for is actual proof.
     
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