• Chinese Physics B
  • Vol. 29, Issue 8, (2020)
Genyan Li1、2、3, Xiao Li4, Lei Zhang2、3、5, and Jun Chen1、2、3、†
Author Affiliations
  • 1Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, China
  • 2State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Taiyuan 030006, China
  • 3Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 00006, China
  • 4Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
  • 5Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
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    DOI: 10.1088/1674-1056/ab9616 Cite this Article
    Genyan Li, Xiao Li, Lei Zhang, Jun Chen. Gain-induced large optical torque in optical twist settings[J]. Chinese Physics B, 2020, 29(8): Copy Citation Text show less

    Abstract

    Inducing a significant optical torque remains a challenging task, since the law of angular momentum conservation implies that one has to harvest a lot of light. Such a problem was partially resolved by using optical twist via strong internal multiple scattering to recycle the photons, and one can induce a large torque per unit of radiation cross section. By using the Maxwell stress tensor and the generalized Lorentz–Mie scattering theory for multi-spheres, we investigate the influence of gain materials in further amplifying optical torque in the optical twist settings. It is found that, when combined with a gain layer, the optical torque of lossy (both in PT - and non-PT-symmetric structures) or lossless (low dielectric materials) clusters at resonance could be one order of magnitude larger than those of a single layer and previous studied plasmonic double layer structures. Moreover, the gain-enhanced large opposite rotations (i.e., optical twist) of the two layers arise at resonances in these structures. In contrast, in the gain–gain double-layer cluster, optical torques on both layers have no significant increase and the two layers rotate in the same direction at resonances. This work provides an elaborate investigation on the gain media-induced optical twist, which offers more choices for optical micromanipulation.
    Genyan Li, Xiao Li, Lei Zhang, Jun Chen. Gain-induced large optical torque in optical twist settings[J]. Chinese Physics B, 2020, 29(8):
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