Presentation Information
[23p-11F-17]Effect of defocusing on plasmonic response of nanoparticle
〇(DC)Sarita Mehra1, Rajan Jha2, Rakesh Kumar Singh1 (1.IIT-BHU, Varanasi, 2.IIT-Bhubaneswar)
Keywords:
Plasmonics,Tight focusing of beams,Nanophotonics
Tightly focused beam scattering through a nanoparticle (NP) influences their plasmonic properties and shows significant intensity enhancement in the near-field of the NP. Such beams with high numerical aperture (NA) and high convergence angle can produce a tight focal spot. Deviation of the incident beam wave-front from its actual reference sphere is referred as aberration which may arise due to various reasons, and improper positioning of the detector plane is one of them which results in defocusing. However, defocusing is a common problem which affects the quality of beam structure around the focal point. The wave aberration caused due to defocusing is described using Zernike polynomial. In this work, we examine influence of defocusing on scattering due to NPs in a high NA system with different convergence angles. A tightly focussed linearly polarized beam is considered for illuminating a plasmonic silver NP. Intensity enhancement in near-field is examined in the presence of defocusing in the optical system.