Negative refractive index

[Jay-qu]

So apparently there are these metamaterials that posses a negative refractive index such that light will refract to the opposite side of the normal..

 

this is where I get caught up: metamaterials have ε < 0 and μ < 0

so if [math] N=\sqrt{\epsilon\mu}[/math] how is that that you can get a negative N ?

[kmarinas86]

I'm not sure, but I think it has to do with the formula for a "complex refractive index." What you have there is not the complete deal.

[Jay-qu]

slight *bump* I was hoping for some explanation..

 

any way if you want to know more try metamaterials

[Erasmus00]

this is where I get caught up: metamaterials have ε < 0 and μ < 0

so if [math] N=\sqrt{\epsilon\mu}[/math] how is that that you can get a negative N ?

 

When you take a square root, you get two answers, one positive, one negative.

 

The reason you need to take the negative square root for a material with a negative dielectric and magnetic constant is that when you try and satisfy the boundary conditions for a wave traveling through the surface, you'll find that the group velocity of the wave is anti-parallel to the phase velocity.

-Will

[Qfwfq]

I would find that understandable if dispersivity were being discussed, rather than given values of ε and μ. Do you have a link to something that spells it out more?

[Jay-qu]

just the wiki on metamaterials :shrug:

[Erasmus00]

I would find that understandable if dispersivity were being discussed, rather than given values of ε and μ. Do you have a link to something that spells it out more?

 

Jackson does a bit on negative refractive indices in his chapter on wave propagation, and I think in his chapter on linear response. I'd give chapter numbers, but I'm on the road and don't have my texts with me.

-Will