Negative Refractivity for Optical Computing

zero_offset writes "This article in EE Times details Purdue's efforts to create a material with negative refractivity. One of the important results would be the ability to create optical computers due to the effect's tendency to amplify and focus light at wavelengths larger than the thickness of the nanowires used in the transmission system. Purdue's School of Electrical and Computer Engineering's Vladimir Shalaev says, "Using these plasmonic nanomaterials, we hope to directly manipulate light, guide it around corners with no losses and basically do all the fundamental operations we do with electronic circuits today, but with photons instead." Nanowires, surface plasmon polaritons, optical computers, nanoscale metamaterials, unnatural refractivity -- what's not to like?" We did a story on the first material known to have a negative index of refraction last year.

Comments

Some Claims are absurd

[slashnot007]

Much of what is claimed in the article and comapnion article is wrong, no doubt distorted through the prism of some "science writer" or attempt to dumb it down. For exampe, you cant focus light to a perfect point or even less that the wavelength of light.
the ways one can escape these limits in a semantic sense is that you can change the index of refration of the media so the wavelength is shorter than in vaccum, but that's not really accomnlishing the goal. Alternatively, near field or or ther diffraction effects can confine a light field to a region smaller the wavelength, but it cant propagate in vacuum/air that way.

likewise the claim you could make a perfecly flat focusing lens by combining poistive and negative materials is pretty hilarious too. You can do that right now with conventional positive only materials. (example take two plano confave lenses of high index material, and fill the space between them with water. voila!).

on the other hand you could do a lot of really interesting stuff with negative index materials that is harder to put in laymans terms. one example, the speed of light might be faster than in vacuum.

Re:Meaning?

[guybarr]

I thought the index of refraction was defined as:

n = (speed of light in vacuum)/(speed of light in medium),

another definition, IIRC, is c/sqrt(mu*epsilon)

mu = permeability
epsilon = permittivity

both are coeeficients of the linear response of meterials to the EM field.

now, if the linear response of a material to EM fields is complex, I guess you can have negative (or imaginary) n.

imaginary means exponential decay or growth, BTW, but of course in the case of growth the material stops responding linearly at some point, thus changing the dependance.

IIAC, negative n does not really mean the speed of light reverses .

Now, convenctional wisdom and all modern science says c is always the bigger value, so n is always >= 1

AFAIK you're right in saying c is always the bigger value, however there exist superluminal photons , which have phase velocity higher than c.

This is not, again AFAIK, related to the response medium but to other quantum phenomenas.

The universe can do some weird, convoluted vodoo ...

What negative refraction means

[zero_offset]

For those of you trying to figure out what "negative refraction" actually implies, the article at the URL below has a pretty easy-to-understand explanation of the key characteristics.

03/2001 photonics.com article