Open AccessSecond-harmonic generation from subwavelength metal heterodimers
Author(s) -
Maya Hen Shor Peled,
Esti Toledo,
Shilpi Shital,
Achyut Maity,
Mandira Pal,
Yonatan Sivan,
Mark Schvartzman,
Avi Niv
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.405247
Subject(s) - second harmonic generation , materials science , nonlinear optics , sum frequency generation , optics , metal , molecular physics , coulomb , optoelectronics , physics , laser , electron , quantum mechanics , metallurgy
We experimentally study the optical second-harmonic generation (SHG) from deep subwavelength gold-silver heterodimers, and silver-silver and gold-gold homodimers. Our results indicate a heterodimer SHG that is an order of magnitude more intense than that of the homodimers. In contrast, full-wave calculations that consider the surface and bulk contribution of individual particles, which is the conventional view on such processes, suggest that it is the silver-silver homodimer that should prevail. Based on the deep subwavelength dimension of our structure, we propose that the heterodimer nonlinearity results from a Coulomb interaction between lumped oscillating charges and not from the surface nonlinearity of each particle, as convention would have it. Our proposed model can explain the larger SHG emission observed in gold-silver heterodimers and reproduces its unique spectral lineshape.