Enhancing plasmonic response by scattering of a beam under spherical aberration

• Published in: Optics and laser technology 2024-12, Vol.179, p.111397, Article 111397
• Main Authors: Sarita, Jha, Rajan, Kumar Singh, Rakesh
• Format: Article
• Language: English
• Subjects: Defocusing; Localized surface plasmon resonance; Mie scattering; Spherical aberration; Tight focusing
• ISSN: 0030-3992
• DOI: 10.1016/j.optlastec.2024.111397

•Mie theory and multipole expansion approach for interaction of beam with nanoparticles.•Scattering of tightly focused beams under spherical aberration through nanoparticles.•Results on the spherical aberration and defocusing in a balancing condition.•Analysis of radial and tangential components of near-field intensity enhancement. The plasmonic response of a spherically symmetric nanoparticle is theoretically analysed using the Mie theory and multipole expansion for a tightly focused beam under the spherical aberration and defocusing. It is observed that the spherical aberrations present in the system amend the absorption and scattering efficiency of the nanoparticles, and the electromagnetic field around the nanoparticle. An enhancement in the near-field intensity appears due to excitement of plasmons on the surface of a nanoparticle and this is further increased for a beam under spherical aberration. In contrast to the aberration free case where radial component was dominating in the near field intensity enhancement, presence of spherical aberration in the focusing system significantly enhances the contribution of the tangential component in addition to the radial component. Defocusing aberration is also introduced to compensate the effect of spherical aberration and results are presented for the balancing condition.