December 07, 2006

Plasmons - bridging optics and electronics

New light physics with plasmons that could bridge light, matter and electronics. Plasmon computers could operate at 100 Terahertz - 1000 terahertz or 20,000 to 200,000 times faster than mainstream computer chips. Part of what I think is the growing trend of greater control of all information, light, energy, matter and magnetism. (ILEMM)

Two-dimensional light, or plasmons, can be triggered when light strikes a patterned metallic surface. Plasmons (wikipedia) may well serve as a proxy for bridging the divide between photonics (high throughput of data but also at the relatively large circuit dimensions of one micron, or one thousandth of a millimeter) and electronics (relatively low throughput but tiny dimensions of tens of nanometers, or millionths of a millimeter).

One might be able to establish a hybrid discipline, plasmonics, in which light is first converted into plasmons, which then propagate in a metallic surface but with a wavelength smaller than the original light; the plasmons could then be processed with their own two-dimensional optical components (mirrors, waveguides, lenses, etc.), and later plasmons could be turned back into light or into electric signals.

Plasmon microscope:

Igor Smolyaninov (University of Maryland, reported that he and his colleagues were able to image tiny objects lying in a plane with spatial resolution as good as 60 nm (when mathematical tricks are applied, the resolution becomes 30 nm) using plasmons that had been excited in that plane by laser light at a wavelength of 515 nm. In other words, they achieve microscopy with a spatial resolution much better than diffraction would normally allow; furthermore, this is far-field microscopy -- the light source doesn't have to be located less than a light-wavelength away from the object.

This work is essentially a Flatland version of optics. They use 2D plasmon mirrors and lenses to help in the imaging and then conduct plasmons away by a waveguide.

Future plasmon circuits at optical frequencies:

Nader Engheta (University of Pennsylvania, argued that nano-particles, some supporting plasmon excitations, could be configured to act as nm-sized capacitors, resistors, and inductors -- the basic elements of any electrical circuit.

The circuit in this case would be able to operate not at radio (10**10 Hz) or microwave (10**12 Hz) frequencies but at optical (10**15 Hz) frequencies. This would make possible the miniaturization and direct processing of optical signals with nano-antennas, nano-circuit-filters, nano-waveguides, nano-resonators, and may lead to possible applications in nano-computing, nano-storage, molecular signaling, and molecular-optical interfacing.

More physics papers on plasmons



Jonathan Pugh said...

Sounds like most of todays work goes in line with allowing components to talk with each other faster than the old school copper wires.

physorg had an article on indium gallium arsenide transistors to replace silicon ones:

Do you think that InGaAs transistors will come about before spintronic based transister computers? Or will we be close to hitting the wall with silicon transistors and paradigm shift directly to spintronics? I believe you said that we are still about 15 years out for spintronic computers...

bw said...

I think InGaAs transistors will find a niche. It could be a big niche worth billions but I would be very surprised see it taking over from silicon. InGaAs uses more current for faster speed. The trend now is to get more performance out of less power. Therefore, I see InGaAs being a small niche player. It has to have some kind of applications where it is clearly vastly superior.

Silicon semiconductors have hundreds of billions going into infrastructure, research and trained personnel.

Spintronics will be coming into the memory space and could come into processing. In some niche at first. In order for them to become dominant for our personal computer industry the spintronics or any other technology needs to be easily adopted by the existing people and companies.

Think of how hard it is for regular people to stop using oil for cars. This is similar to the issues of replacing silicon. Except silicon does not have all the downsides of oil and silicon improves with a double in performance every 18-24 months.

Spintronics I see coming into more things because it is a more general physical property based set of technologies. It is already getting into memory. It can develop scale. It has a lot of performance advantages and enables some completely new things. Completely new capabilities means less competition.