Definition of spaser

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Photonics Dictionary

spaser: A spaser (surface plasmon amplification by stimulated emission of radiation) is a nanoscale device that generates coherent optical radiation at nanometer-scale dimensions. It is analogous to a laser but operates on the principles of surface plasmon resonance (SPR) rather than traditional optical gain mechanisms.

Surface plasmons: Surface plasmons are collective oscillations of free electrons at the interface between a metal and a dielectric material, typically occurring when light interacts with metallic nanostructures at the nanoscale. These surface plasmons can confine and manipulate electromagnetic fields at subwavelength dimensions, leading to enhanced light-matter interactions.

Amplification by stimulated emission: In a spaser, the excitation of surface plasmons can lead to population inversion in certain gain media (e.g., quantum dots or dye molecules) embedded within or near the metallic nanostructure. When properly stimulated by external electromagnetic fields, these gain media can emit coherent optical radiation, resulting in spaser action.

Nanoscale dimensions: Spasers operate at the nanoscale, with dimensions typically smaller than the wavelength of light. This enables them to confine and manipulate light at extremely small spatial scales, making them potentially useful for nanophotonic applications, including sensing, imaging, and information processing.

Enhanced light-matter interactions: Due to their ability to concentrate electromagnetic fields into nanoscale volumes, spasers can enhance light-matter interactions, such as absorption, scattering, and emission processes. This property has implications for various fields, including plasmonics, sensing, and spectroscopy.

Spasers have attracted significant research interest due to their potential for enabling new technologies and applications at the nanoscale. However, practical challenges remain in terms of achieving stable and efficient spaser operation, as well as integrating spasers into functional devices and systems. Nonetheless, ongoing research efforts continue to advance our understanding of spaser physics and explore their capabilities for future nanophotonic applications.

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