Mode broadening induced by nanoparticles in an optical whispering-gallery microcavity

Yuwen Hu, Linbo Shao, Stephen Arnold, Yong-Chun Liu, Cao-Yuan Ma, and Yun-Feng Xiao
Phys. Rev. A 90, 043847 – Published 21 October 2014

Abstract

We theoretically investigate mode broadening of a high-Q optical whispering-gallery microcavity coupled to a single or multiple dielectric or plasmonic subwavelength particles. The result shows that backscattering contributes dominantly to the mode broadening in both transmission and reflection spectra for dielectric particles binding on the microcavity surface, while absorption also plays an important role for lossy nanoparticles. The mode broadening induced by nanoparticles holds great potential in optical biosensing. For instance, by monitoring the change of mode linewidth, a single 11-nm-radius spherical polystyrene nanoparticle is detectable. This detection breaks through the detection limit of the mode-splitting method using a passive cavity and remains immune to various noises, such as thermal fluctuations and frequency drifts of the probe laser. Finally, the mode broadening is demonstrated to be particularly suitable for detecting lossy nanoparticles, e.g., plasmonic particles.

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  • Received 28 May 2014
  • Revised 29 August 2014

DOI:https://doi.org/10.1103/PhysRevA.90.043847

©2014 American Physical Society

Authors & Affiliations

Yuwen Hu1, Linbo Shao1, Stephen Arnold2, Yong-Chun Liu1, Cao-Yuan Ma1, and Yun-Feng Xiao1,3,*

  • 1State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871, People's Republic of China
  • 2New York University Polytechnic School of Engineering, Brooklyn, New York 11201, USA
  • 3Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China

  • *yfxiao@pku.edu.cn; www.phy.pku.edu.cn/∼yfxiao/index.html

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Issue

Vol. 90, Iss. 4 — October 2014

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