Abstract
Interactions between whispering gallery modes (WGMs) and small nanoparticles are commonly modeled by treating the particle as a point dipole scatterer. This approach is assumed to be accurate as long as the nanoparticle radius, , is small compared to the WGM wavelength . In this Letter, however, we show that the large field gradients associated with the evanescent decay of a WGM causes the dipole theory to significantly underestimate the interaction strength and, hence, the induced WGM resonance shift, even for particles as small as . To mitigate this issue, we employ a renormalized Born approximation to more accurately determine nanoparticle-induced resonance shifts and, hence, enable improved particle sizing. The domain of validity of this approximation is investigated, and supporting experimental results are presented.
© 2017 Optical Society of America
Full Article | PDF ArticleMore Like This
Jiangang Zhu, Şahin Kaya Özdemir, Lina He, Da-Ren Chen, and Lan Yang
Opt. Express 19(17) 16195-16206 (2011)
Lev Deych and Lan Yang
Opt. Lett. 45(6) 1435-1438 (2020)
Lev Deych and Vladimir Shuvayev
Opt. Lett. 40(19) 4536-4539 (2015)