Localized surface plasmon singularities in amplifying media

Abstract

The localized surface plasmon resonance of nanostructures is shown to exhibit a singularity when the surrounding medium exhibits amplification with a critical value of gain. This singularity can lead to large enhancements even when the gain is saturated. This composite medium should exhibit strong scattering within the plasmon band leading to low threshold random laser action and light localization effects. This effect could also greatly increase surface enhanced Raman scattering signals for rapid single, molecule detection, identification and sequencing.

Engineering of low-loss metal for nanoplasmonic and metamaterials applications

“…It has been shown theoretically [16][17][18] and experimentally [19][20][21][22] that the optical loss in metallic nanostructures can be compensated and the stimulated emission of surface plasmons (SPs) can be obtained if the optical gain is added to an adjacent dielectric.…”

Reducing the losses of optical metamaterials

“…However, to check if losses in metamaterials can be reduced experimentally, one can try exploratory experiments under conditions of optical pumping. While early models [68,74,[123][124][125] using simplified gain-mechanisms such as explicitly forcing negative imaginary parts of the local gain material's response function produce unrealistic strictly linear gain, our self-consistent approach presented below allows for determining the range of parameters for which one can realistically expect linear amplification and linear loss compensation in the metamaterial [80][81][82]. The approximation in these earlier models can effectively be obtained in our approach by assuming a constant population inversion in Eq.…”

“…The dream would be to simply inject an electrical current into the active medium, leading to gain and hence to compensation of the losses. One important issue is not to assume the metamaterial layer and the gain medium layer are independent from one another [68,72,[74][75][76][77][78][79]123]. So, experiments on such intricate active nanostructures do need guidance by theory via self-consistent calculations [80][81][82][83] (using the semi-classical theory of lasing) for realistic gain materials that can be incorporated into or close to dispersive media to reduce the losses at THz or optical frequencies.…”

Albedo and gain threshold of a diffusive Raman random laser

“…A number of non-linear optical effects have been observed in random laser media via the enhanced interaction arising from multiple scattering and gain, namely second and higher harmonic generation [1][2][3], anti-Stokes random lasing [4], up-conversion lasing [5] and surface plasmon enhanced Raman scattering [6] and random lasing [7].…”