Spaser
Encyclopedia
SPASER is an acronym for "surface plasmon
amplification by stimulated emission
of radiation". The phenomenon was first described by Bergman and Stockman in 2003 The first such device was announced in August 2009, a 44-nanometer-diameter nanoparticle with a gold
core surrounded by a dyed silica gain medium, created by researchers from Purdue, Norfolk State and Cornell universities.
The spaser is a proposed nanoscale source of optical field
s that is being investigated in a number of leading laboratories around the world. If realized, spasers could find a wide range of applications, including nanoscale lithography
, probing and microscopy.
The following is an excerpt from :
"A spaser is the nanoplasmonic counterpart of a laser
, but it (ideally) does not emit photons. It is analogous to the conventional laser, but in a spaser photons are replaced by surface plasmons and the resonant cavity is replaced by a nanoparticle, which supports the plasmonic modes. Similarly to a laser, the energy source for the spasing mechanism is an active (gain) medium that is excited externally. This excitation field may be optical and unrelated to the spaser’s operating frequency; for instance, a spaser can operate in the near-infrared
but the excitation of the gain medium can be achieved using a ultraviolet
pulse.
The reason that surface plasmons in a spaser can work analogously to photons in a laser is that their relevant physical properties are the same. First, surface plasmons are bosons: they are vector excitations and have spin
1, just as photons do. Second, surface plasmons are electrically neutral excitations. And third, surface plasmons are the most collective material oscillations known in nature, which implies they are the most harmonic (that is, they interact very weakly with one another). As such, surface plasmons can undergo stimulated emission, accumulating in a single mode in large numbers, which is the physical foundation of both the laser and the spaser."
Study of the quantum mechanical model of the spaser suggests that it should be possible to manufacture a spasing device analogous in function to the MOSFET
transistor , but this has not yet been experimentally verified.
Surface plasmon
Surface plasmons , are coherent electron oscillations that exist at the interface between any two materials where the real part of the dielectric function changes sign across the interface...
amplification by stimulated emission
Stimulated emission
In optics, stimulated emission is the process by which an atomic electron interacting with an electromagnetic wave of a certain frequency may drop to a lower energy level, transferring its energy to that field. A photon created in this manner has the same phase, frequency, polarization, and...
of radiation". The phenomenon was first described by Bergman and Stockman in 2003 The first such device was announced in August 2009, a 44-nanometer-diameter nanoparticle with a gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
core surrounded by a dyed silica gain medium, created by researchers from Purdue, Norfolk State and Cornell universities.
The spaser is a proposed nanoscale source of optical field
Optical field
The optical field is a term used in physics and vector calculus to designate the electric field shown as E in the electromagnetic wave equation which can be derived from Maxwell's Equations...
s that is being investigated in a number of leading laboratories around the world. If realized, spasers could find a wide range of applications, including nanoscale lithography
Nanolithography
Nanolithography is the branch of nanotechnology concerned with the study and application of fabricating nanometer-scale structures, meaning patterns with at least one lateral dimension between the size of an individual atom and approximately 100 nm...
, probing and microscopy.
The following is an excerpt from :
"A spaser is the nanoplasmonic counterpart of a laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
, but it (ideally) does not emit photons. It is analogous to the conventional laser, but in a spaser photons are replaced by surface plasmons and the resonant cavity is replaced by a nanoparticle, which supports the plasmonic modes. Similarly to a laser, the energy source for the spasing mechanism is an active (gain) medium that is excited externally. This excitation field may be optical and unrelated to the spaser’s operating frequency; for instance, a spaser can operate in the near-infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
but the excitation of the gain medium can be achieved using a ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
pulse.
The reason that surface plasmons in a spaser can work analogously to photons in a laser is that their relevant physical properties are the same. First, surface plasmons are bosons: they are vector excitations and have spin
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
1, just as photons do. Second, surface plasmons are electrically neutral excitations. And third, surface plasmons are the most collective material oscillations known in nature, which implies they are the most harmonic (that is, they interact very weakly with one another). As such, surface plasmons can undergo stimulated emission, accumulating in a single mode in large numbers, which is the physical foundation of both the laser and the spaser."
Study of the quantum mechanical model of the spaser suggests that it should be possible to manufacture a spasing device analogous in function to the MOSFET
MOSFET
The metal–oxide–semiconductor field-effect transistor is a transistor used for amplifying or switching electronic signals. The basic principle of this kind of transistor was first patented by Julius Edgar Lilienfeld in 1925...
transistor , but this has not yet been experimentally verified.