Thread Closed

Negative Refractive index!!!

 
Share Thread Thread Tools
Nov2-04, 11:06 PM   #1
 
Exclamation

Negative Refractive index!!!


Is negative refractive index possible(theoretically,in optics). If so what are its implications?
PhysOrg.com
PhysOrg
physics news on PhysOrg.com

>> As chaos celebrates its 50th birthday, biophysicist develops a new method to visualize it
>> Novel features of helium-3 superfluidity discovered with new SQUID detector chip
>> Physics of 'green waves' could make city traffic flow more smoothly
Nov3-04, 04:39 AM   #2
 
Recognitions:
Homework Helper Homework Help
Science Advisor Science Advisor
The angle of incidence and the angle of refraction are always between 0 and pi, so their sine is never negative.
If I look at Snell's law:
[tex]\frac{\sin\theta_i}{\sin\theta_t}=\frac{n_t}{n_i}[/tex]
where [itex]n_i,n_t[/itex] are the refractive indices, the answer is clearly no. It wouldn't make physical sense.
Nov3-04, 06:33 AM   #3
 
Negative refractive index has been demonstrated in some meta-material recently, it's still a hot topic of research though. Have a look at http://physicsweb.org/articles/news/7/10/10 and http://physics.ucsd.edu/lhmedia/. There're a whole lot more information available by googling.
Snells law still holds, by inserting a negative n you'll get a negative angle, meaning that the refraction angle is actually on the same side as the incident angle.
Nov3-04, 09:55 AM   #4
 
Recognitions:
Homework Helper Homework Help
Science Advisor Science Advisor

Negative Refractive index!!!




Pretty cool.

That's why I love physics.
Nov7-04, 06:48 PM   #5
 
Recognitions:
Science Advisor Science Advisor
The Kramers-Kronig relationships also predict regions of the spectrum where the refractive index of a material is negative, however, these regions also correspond to regions of high absorption (It is argued that because of this, relativity is not violated).

Claude.
Dec9-04, 03:16 PM   #6
 
When a material doesn't propagate a wave and doesn't absorb it, it has a negative refractive index.

In that case, the wave impiging on the material doesn't penetrate much inside the material.
Typically over a fraction of wavelength to a few wavelengths. The wave is said "evanescent".

Plasmas offer a good exemple. Below the 'plasma frequency' no wave can propagate. For higher frequency propagation is the rule.
In magnetised plasma things are much more complex.
There are bands of evanescence and bands of propagation. In additions, these bands depend on the direction of the wave and the polarisation.
The refractive index is then a matrix called "dielectric tensor".
Thread Closed
Thread Tools


Similar Threads for: Negative Refractive index!!!
Thread Forum Replies
Refractive index Introductory Physics Homework 3
?? Refractive Index ?? Materials & Chemical Engineering 3
Refractive index Introductory Physics Homework 1
Negative Refractive Index Telescopes? General Astronomy 1
Negative Refractive Index General Physics 1