title: Radiation-pressure-induced nonlinearity in microdroplets.
abstract: High quality (Q) factor whispering gallery modes (WGMs) can induce nonlinear effects in liquid droplets through mechanisms such as radiation pressure, Kerr nonlinearity, and thermal effects. However, such nonlinear effects, especially those due to radiation pressure, have yet to be thoroughly investigated and compared in the literature. In this study, we present an analytical approach that can exactly calculate the droplet deformation induced by the radiation pressure. The accuracy of the analytical approach is confirmed through numerical analyses based on the boundary element method. We show that the nonlinear optofluidic effect induced by the radiation pressure is stronger than the Kerr effect and the thermal effect under a large variety of realistic conditions. Using liquids with ultralow and experimentally attainable interfacial tension, we further confirm the prediction that it may only take a few photons to produce measurable WGM resonance shift through radiation-pressure-induced droplet deformation.
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Sunghwan
authors.initials: S
authors.lastname: Jung
authors.affiliation: Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Aram
authors.initials: A
authors.lastname: Lee
authors.affiliation: Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu