A View from Emerging Technology from the arXiv
Plasmonic Laser Heralds New Generation of Computing
There has never been a plasmonic device that can amplify and process information. Until now.
If you’re into buzzwords, nanoplasmonics is one you ought to know about. Nanoplasmonics, we’re told, is the next big thing–the field that will allow us to sense and manipulate the world on the smallest of scales.

Plasmons, of course, are waves in the sea of free electrons inside and on the surface of metals. These waves are nanoscopic in size and have a frequency measured in attoseconds (equivalent to the optical range of UV to infrared). They are quantized, which means they can demonstrate the strange properties of quantum mechanics. And they are incredibly sensitive to the world around them. This makes plasmons perfect for sensing everything from photons, magnetic fields and electrons. They promise a new generation of photodetectors, scanning microscopes and various biomedical devices.
But there’s a problem. There is currently no active device that
can generate and amplify nanoplasmonic signals to make them easier to
monitor.
What’s needed, says Mark Stockman at the Max Planck
Institute for Quantum Optics in Germany, is the nanoplasmonic
equivalent of a transistor and he has come up with a device that can
do the trick.
His device is the nanoplasmonic equivalent of a
laser. He calls it a spaser (Surface Plasmon Amplification by
Stimulated Emission of Radiation). In a spaser, a surface plasmon
plays the same role as a photon in a laser.
So the idea is
that a plasmon enters a resonator in the form of a nanoparticle that
is embedded in some kind of gain material containing chromophores
such as semiconductor nanocrystals or dye molecules. Obviously, the
gain medium must be capable of population inversion which allows it
to lase (or “spase” in this case).
Stockman
introduced the idea of a spaser a few years ago and the first one was
built earlier this year by a group in the US. But today, Stockman
reveals its full power in the first full quantum mechanical
description of the device. And it looks mighty useful too.
A
spaser is, in effect, a nanoscale plasmon amplifier. But it can also
generate plasmons as well as store them. That’s roughly what an
ordinary field effect transistor does with electrons but Stockman has
calculated that it can do all this roughly three orders of magnitude
faster. Yep, that’s a thousand times faster.
Stockman has an
powerful vision for his device:
“One may envision ultrafast nanoplasmonic chips with a high degree of integration where spasers communicate and control each other through their near fields or are connected with nanoplasmonic wires. These can perform ultrafast microprocessor functions.”
What he’s describing, of course, is a new generation of
ultrafast computers based on plasmonics.
That’s ambitious.
What he’ll need are powerful backers with deep pockets and he might
just get them. Because spasers are based on metals rather than
semiconductors, they are much more resistant to ionising radiation.
That means they will be of special interest to the nuclear and
aerospace industries and of course to the military.
Expect to
hear a lot more about them.
Ref: arxiv.org/abs/0908.3559: Spaser as Nanoscale Quantum Generator and Ultrafast Amplifier