Spaser

Last updated

A spaser or plasmonic laser is a type of laser which aims to confine light at a subwavelength scale far below Rayleigh's diffraction limit of light, by storing some of the light energy in electron oscillations called surface plasmon polaritons. [1] [2] [3] [4] [5] The phenomenon was first described by David J. Bergman and Mark Stockman in 2003. [6] The word spaser is an acronym for "surface plasmon amplification by stimulated emission of radiation". [6] The first such devices were announced in 2009 by three groups: 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, [7] a nanowire on a silver screen by a Berkeley group, [1] and a semiconductor layer of 90 nm surrounded by silver pumped electrically by groups at the Eindhoven University of Technology and at Arizona State University. [4] While the Purdue-Norfolk State-Cornell team demonstrated the confined plasmonic mode, the Berkeley team and the Eindhoven-Arizona State team demonstrated lasing in the so-called plasmonic gap mode. In 2018, a team from Northwestern University demonstrated a tunable nanolaser that can preserve its high mode quality by exploiting hybrid quadrupole plasmons as an optical feedback mechanism. [8]

Contents

The spaser is a proposed nanoscale source of optical fields that is being investigated in a number of leading laboratories around the world. Spasers could find a wide range of applications, including nanoscale lithography, fabrication of ultra-fast photonic nano circuits, single-molecule biochemical sensing, and microscopy. [5]

From Nature Photonics: [9]

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 an 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, [10] but this has not yet been experimentally verified.

See also

Related Research Articles

<span class="mw-page-title-main">Plasmon</span> Quasiparticle of charge oscillations in condensed matter

In physics, a plasmon is a quantum of plasma oscillation. Just as light consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quantization of plasma oscillations, just like phonons are quantizations of mechanical vibrations. Thus, plasmons are collective oscillations of the free electron gas density. For example, at optical frequencies, plasmons can couple with a photon to create another quasiparticle called a plasmon polariton.

<span class="mw-page-title-main">Polariton</span> Quasiparticles arising from EM wave coupling

In physics, polaritons are quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole-carrying excitation. They are an expression of the common quantum phenomenon known as level repulsion, also known as the avoided crossing principle. Polaritons describe the crossing of the dispersion of light with any interacting resonance. To this extent polaritons can also be thought of as the new normal modes of a given material or structure arising from the strong coupling of the bare modes, which are the photon and the dipolar oscillation. The polariton is a bosonic quasiparticle, and should not be confused with the polaron, which is an electron plus an attached phonon cloud.

Nanophotonics or nano-optics is the study of the behavior of light on the nanometer scale, and of the interaction of nanometer-scale objects with light. It is a branch of optics, optical engineering, electrical engineering, and nanotechnology. It often involves dielectric structures such as nanoantennas, or metallic components, which can transport and focus light via surface plasmon polaritons.

<span class="mw-page-title-main">Extraordinary optical transmission</span>

Extraordinary optical transmission (EOT) is the phenomenon of greatly enhanced transmission of light through a subwavelength aperture in an otherwise opaque metallic film which has been patterned with a regularly repeating periodic structure. Generally when light of a certain wavelength falls on a subwavelength aperture, it is diffracted isotropically in all directions evenly, with minimal far-field transmission. This is the understanding from classical aperture theory as described by Bethe. In EOT however, the regularly repeating structure enables much higher transmission efficiency to occur, up to several orders of magnitude greater than that predicted by classical aperture theory. It was first described in 1998.

<span class="mw-page-title-main">Surface plasmon</span>

Surface plasmons (SPs) are coherent delocalized electron oscillations that exist at the interface between any two materials where the real part of the dielectric function changes sign across the interface. SPs have lower energy than bulk plasmons which quantise the longitudinal electron oscillations about positive ion cores within the bulk of an electron gas.

Plasmonic nanolithography is a nanolithographic process that utilizes surface plasmon excitations such as surface plasmon polaritons (SPPs) to fabricate nanoscale structures. SPPs, which are surface waves that propagate in between planar dielectric-metal layers in the optical regime, can bypass the diffraction limit on the optical resolution that acts as a bottleneck for conventional photolithography.

A nanolaser is a laser that has nanoscale dimensions and it refers to a micro-/nano- device which can emit light with light or electric excitation of nanowires or other nanomaterials that serve as resonators. A standard feature of nanolasers includes their light confinement on a scale approaching or suppressing the diffraction limit of light. These tiny lasers can be modulated quickly and, combined with their small footprint, this makes them ideal candidates for on-chip optical computing.

<span class="mw-page-title-main">Surface plasmon polariton</span> Electromagnetic waves that travel along an interface

Surface plasmon polaritons (SPPs) are electromagnetic waves that travel along a metal–dielectric or metal–air interface, practically in the infrared or visible-frequency. The term "surface plasmon polariton" explains that the wave involves both charge motion in the metal and electromagnetic waves in the air or dielectric ("polariton").

A plasmonic metamaterial is a metamaterial that uses surface plasmons to achieve optical properties not seen in nature. Plasmons are produced from the interaction of light with metal-dielectric materials. Under specific conditions, the incident light couples with the surface plasmons to create self-sustaining, propagating electromagnetic waves known as surface plasmon polaritons (SPPs). Once launched, the SPPs ripple along the metal-dielectric interface. Compared with the incident light, the SPPs can be much shorter in wavelength.

A polariton laser is a novel type of laser source that exploits the coherent nature of Bose condensates of exciton-polaritons in semiconductors to achieve ultra-low threshold lasing.

In nano-optics, a plasmonic lens generally refers to a lens for surface plasmon polaritons (SPPs), i.e. a device that redirects SPPs to converge towards a single focal point. Because SPPs can have very small wavelength, they can converge into a very small and very intense spot, much smaller than the free space wavelength and the diffraction limit.

Photonic molecules are a form of matter in which photons bind together to form "molecules". They were first predicted in 2007. Photonic molecules are formed when individual (massless) photons "interact with each other so strongly that they act as though they have mass". In an alternative definition, photons confined to two or more coupled optical cavities also reproduce the physics of interacting atomic energy levels, and have been termed as photonic molecules.

Ortwin Hess is a German-born theoretical physicist at Trinity College Dublin (Ireland) and Imperial College London (UK), working in condensed matter optics. Bridging condensed matter theory and quantum optics he specialises in quantum nanophotonics, plasmonics, metamaterials and semiconductor laser dynamics. Since the late 1980s he has been an author and coauthor of over 300 peer-reviewed articles, the most popular of which, called "'Trapped rainbow' storage of light in metamaterials", was cited more than 400 times. He pioneered active nanoplasmonics and metamaterials with quantum gain and in 2014 he introduced the "stopped-light lasing" principle as a novel route to cavity-free (nano-) lasing and localisation of amplified surface plasmon polaritons, giving him an h-index of 33.

<span class="mw-page-title-main">Hybrid plasmonic waveguide</span>

A hybrid plasmonic waveguide is an optical waveguide that achieves strong light confinement by coupling the light guided by a dielectric waveguide and a plasmonic waveguide. It is formed by separating a medium of high refractive index from a metal surface by a small gap.

<span class="mw-page-title-main">Plasmonics</span>

Plasmonics or nanoplasmonics refers to the generation, detection, and manipulation of signals at optical frequencies along metal-dielectric interfaces in the nanometer scale. Inspired by photonics, plasmonics follows the trend of miniaturizing optical devices, and finds applications in sensing, microscopy, optical communications, and bio-photonics.

<span class="mw-page-title-main">Electromagnetic metasurface</span>

An electromagnetic metasurface refers to a kind of artificial sheet material with sub-wavelength thickness. Metasurfaces can be either structured or unstructured with subwavelength-scaled patterns in the horizontal dimensions.

Graphene is a 2D nanosheet with atomic thin thickness in terms of 0.34 nm. Due to the ultrathin thickness, graphene showed many properties that are quite different from their bulk graphite counterparts. The most prominent advantages are known to be their high electron mobility and high mechanical strengths. Thus, it exhibits potential for applications in optics and electronics especially for the development of wearable devices as flexible substrates. More importantly, the optical absorption rate of graphene is 2.3% in the visible and near-infrared region. This broadband absorption characteristic also attracted great attention of the research community to exploit the graphene-based photodetectors/modulators.

Spoof surface plasmons, also known as spoof surface plasmon polaritons and designer surface plasmons, are surface electromagnetic waves in microwave and terahertz regimes that propagate along planar interfaces with sign-changing permittivities. Spoof surface plasmons are a type of surface plasmon polariton, which ordinarily propagate along metal and dielectric interfaces in infrared and visible frequencies. Since surface plasmon polaritons cannot exist naturally in microwave and terahertz frequencies due to dispersion properties of metals, spoof surface plasmons necessitate the use of artificially-engineered metamaterials.

<span class="mw-page-title-main">Päivi Törmä</span> Finnish professor of physics

Päivi Törmä is a Finnish physics professor at Aalto University. She works in the fields of quantum many-body physics, superconductivity, and nanophotonics.

Mark Stockman was a Soviet-born American physicist. He was a professor of physics and astronomy at Georgia State University. Best known for his contributions to plasmonics, Stockman has co-theorized plasmonic lasers, also known as spasers, in 2003.

References

  1. 1 2 Oulton, Rupert F.; Sorger, Volker J.; Zentgraf, Thomas; et al. (2009). "Plasmon lasers at deep subwavelength scale" (PDF). Nature. 461 (7264): 629–632. Bibcode:2009Natur.461..629O. doi:10.1038/nature08364. hdl: 10044/1/19116 . ISSN   0028-0836. PMID   19718019. S2CID   912028.
  2. ↑ Ma, Ren-Min; Oulton, Rupert F.; Sorger, Volker J.; et al. (2010). "Room-temperature sub-diffraction-limited plasmon laser by total internal reflection". Nature Materials. 10 (2): 110–113. arXiv: 1004.4227 . Bibcode:2011NatMa..10..110M. doi:10.1038/nmat2919. ISSN   1476-1122. PMID   21170028. S2CID   10624501.
  3. ↑ Noginov, M. A.; Zhu, G.; Belgrave, A. M.; et al. (2009). "Demonstration of a spaser-based nanolaser". Nature. 460 (7259): 1110–1112. Bibcode:2009Natur.460.1110N. doi:10.1038/nature08318. ISSN   0028-0836. PMID   19684572. S2CID   4363687.
  4. 1 2 Hill, Martin; Marell, Milan; Leong, Eunice; et al. (2009). "Lasing in metal-insulator-metal sub-wavelength plasmonic waveguides". Optics Express. 17 (13): 11107–11112. Bibcode:2009OExpr..1711107H. doi: 10.1364/OE.17.011107 . PMID   19550510.
  5. 1 2 Kumar, Pawan; Tripathi, V.K.; Liu, C.S (2008). "A surface plasmon laser". J. Appl. Phys. 104 (3): 033306–033306–4. Bibcode:2008JAP...104c3306K. doi:10.1063/1.2952018.
  6. 1 2 Bergman, David J.; Stockman, Mark I. (2003). "Surface Plasmon Amplification by Stimulated Emission of Radiation: Quantum Generation of Coherent Surface Plasmons in Nanosystems". Phys. Rev. Lett. 90 (2): 027402. Bibcode:2003PhRvL..90b7402B. doi:10.1103/PhysRevLett.90.027402. PMID   12570577. S2CID   10798864.
  7. ↑ Bourzac, Katherine (August 17, 2009). "The Smallest Laser Ever Made". MIT Technology Review.
  8. ↑ Wang, D.; Bourgeois, M.; Lee, W.; et al. (2018). "Stretchable Nanolasing from Hybrid Quadrupole Plasmons". Nano Letters. 18 (7): 4549–4555. Bibcode:2018NanoL..18.4549W. doi:10.1021/acs.nanolett.8b01774. OSTI   1594600. PMID   29912567. S2CID   49302957.
  9. ↑ Stockman, Mark I. (June 2008). "Spasers explained". Nature Photonics. 2 (6): 327–329. Bibcode:2008NaPho...2..327S. doi:10.1038/nphoton.2008.85. ISSN   1749-4885.
  10. ↑ Stockman, Mark I. (2010). "The spaser as a nanoscale quantum generator and ultrafast amplifier". Journal of Optics. 12 (2): 024004. arXiv: 0908.3559 . Bibcode:2010JOpt...12b4004S. doi:10.1088/2040-8978/12/2/024004. ISSN   2040-8978. S2CID   2089181.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.