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Nanolaser

A Nanolaser, also referred to as a miniature laser or plasmonic laser, is a laser, namely a light amplifier by stimulated emission of radiation, that has nanoscale dimensions. While the word nano originates from Greek νᾶνος (=dwarf), the international system of units has adapted the prefix as a quantifier equal to 10-9. The nanolaser concept was developed by Mark Stockman at Georgia State University in 2003.


Description

Traditionally, a beam of light could not be made smaller (or more strongly confined) than about one-half its wavelength, λ. This fundamental physical limitation is called the diffraction limit of light. In order to achieve a laser with optical mode sizes smaller than this limit, scientists needed to invent a novel way of squeezing light in dimensions about 100 times smaller than a diffraction limited beam[1], creating an optical hybridized plasmon-mode. Surface plasmons, light on a metallic interface[2], have the ability to provide strong optical confinement, however they suffer inherent ohmic (resistive) losses. Thus, a nanolaser, while proposed many years ago (as a "plasmon laser")[3] was fundamentally challenging to realize.

A hybrid plasmon approach, however, can combine the best of both words: a strong sub-wavelength optical confinement of nanoscale dimensions with a semiconductor gain medium providing the light amplification. The illustration shows a nanolaser consisting of a semiconductor nanowire forming a cavity, thus providing feedback and the lasing mode confined to 1/100th of the laser wavelength.[4]

Applications

This tiny laser can be modulated quickly and, combined with its small footprint, makes it an ideal candidate for on-chip optical computing. The intense optical fields of such a nanolaser also enables the enhancement effect in non-linear optics or surface-enhanced-raman-scattering (SERS)[5], and therefore paves way towards integrated nanophotonic circuitry.

References

1. ^ Oulton, R. F., Sorger, V. J., Genov, D. A., Pile, D. F. P. & Zhang, X. "A hybrid plasmonic waveguide for sub-wavelength confinement and long-range propagation." Nature Photon. 2, 495–500 (2008)
2. ^ Maier, S. A. Plasmonics, Fundamentals and Applications; Springer: New York, (2007).
3. ^ D. J. Bergman, and M. I. Stockman, Phys. Rev. Lett. 90, 027402 (2003)
4. ^ Oulton, R. F., Sorger, V. J., Zentgraf, T., Ma, R.-M., Gladden, C., Dai, L., Bartal, G. & Zhang, X. "Plasmon lasers at deep subwavelength scale" Nature October (2009)
5. ^ Anker, J. N., Hall, W. P., Lyandres, O., Shah, N. C., Zhao, J. & Van Duyne, R. P. "Biosensing with plasmonic nanosensors." Nature Materials 7, 442 - 453 (2008)


External links

Definition of a Nanolaser

List of laser types

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