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Optical Trapping of Nano-particles by Self-induced Back-action Effect

Abbasi, Mohammad Ali | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49344 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Mehrany, Khashayar
  7. Abstract:
  8. Despite of significant developments of optical trapping in past decays, trapping of small nanometer-sized particle faces some difficulties. Optical force reduces rapidly by decreasing the size of the particle because of reducing the particle’s polarizability. So, it is necessary to increase the intensity of incident beam to attain a stable trap. However, it can lead to damage of particle before getting trapped. Self induced back-action(SIBA) is one of the proposed solutions to overcome this problem. In this phenomena particle plays an active role in trapping by changing the surrounding electromagnetics field. In this thesis, we show that SIBA is a phenomenon that appears when we extend the dipole approximation method to the non-free space. We will investigate this phenomenon by green function analytically and then propose a new numerical method for calculating optical forces in non-free spaces by dipole approximation. In addition, we will investigate trapping of nano-particles in resonators analytically. We show that SIBA will have a significant effect in trapping if !c due to the presence of particle will be greater than the decay rate of cavity(). Besides, we will show that SIBA can lead to cooling of particle in the cavity. At the end, we will propose a theoretical method for investigating trapping and cooling of nano-particles in open resonators
  9. Keywords:
  10. Optical Trapping ; Nanoparticles ; Optical Cooling ; Self-Induced Back-Action (SIBA) Effect ; Dipole Approximation

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