Metamaterials with epsilon and/or mu < 0.

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In summary, there is an interest in creating metamaterials with negative values for epsilon and mu, which results in a negative index of refraction. This means that the group velocity of light is in the opposite direction of the phase velocity. These materials are not naturally found and are created using layers of split-ring resonators and parallel conducting wires.
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yavuznuri
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All known natural materials have epsilon and mu > 0. However, there is an intense effort to manufacture so-called metamaterials, where both of these are <0. In such a case, given n = sqrt[epsilon x mu], one would take the negative root and n is still a real number, but n <0 why do we take the negative?

What is so interesting about this?

What does this say about the propagation of v=c/n, does this mean light is going backwards?
 
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n= √µϵ
n= √(-1) √-1
n= ί ί
n = -1

substances with negative µ and ϵ have some properties differnt from those with positve µ and ϵ and materials eith both µ & ϵ negative are not naturally found .

wavevector is in the direction of phase velocity, it means left handed materials have negative group velocity
 
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  • #3


There is a paper about invisibility which mentioned metamaterials. You said these materials have an index of refraction -1, Does this really mean that light goes backward when it reaches the metamaterial?. Is this really possible?? How could someone create a material with such properties??
 
  • #4


yes in microwave region , electromagnetic wave bends once it reaches to metamaterial .
 
  • #5


thelayman said:
There is a paper about invisibility which mentioned metamaterials. You said these materials have an index of refraction -1, Does this really mean that light goes backward when it reaches the metamaterial?. Is this really possible?? How could someone create a material with such properties??

The phrase "light goes backwards" is somewhat arbitrary because light possesses two velocities, group velocity and phase velocity. A negative index means the group velocity is in the opposite direction to the phase velocity. It is entirely consistent with the laws of electromagnetism as far as I know.

The basic configuration for negative index materials is a layer of split-ring resonators (for negative mu) interspersed by layers of parallel conducting wires (for negative epsilon). The (narrow) wavelength range over which negative refraction is attained depends on the size of the resonators.

Claude.
 

1. What are metamaterials with epsilon and/or mu < 0?

Metamaterials with epsilon and/or mu < 0 are materials engineered to have negative values for their permittivity (epsilon) and/or permeability (mu). This means that these materials have unique properties that cannot be found in naturally occurring materials.

2. How are these metamaterials created?

Metamaterials with epsilon and/or mu < 0 are created by arranging subwavelength structures in a specific pattern to achieve the desired negative values for epsilon and/or mu. These structures can be made of various materials such as metals, ceramics, or polymers.

3. What are the potential applications of these metamaterials?

Metamaterials with epsilon and/or mu < 0 have a wide range of potential applications in fields such as telecommunications, energy, and medicine. They can be used to create superlenses for imaging, antennas with increased bandwidth, and even invisibility cloaks.

4. What challenges are associated with using these metamaterials?

One of the main challenges of using metamaterials with epsilon and/or mu < 0 is the difficulty in manufacturing these materials in large quantities. They also require precise design and fabrication techniques to achieve the desired properties, which can be costly and time-consuming.

5. How could research on these metamaterials impact the future?

The research on metamaterials with epsilon and/or mu < 0 has the potential to revolutionize various industries and technologies in the future. These materials could lead to advancements in telecommunications, energy harvesting, and medical imaging, among others. They could also open up new possibilities for technology that were previously thought to be impossible.

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