Manipulation Of Nanoparticles By Using Vortex Bessel Beams

As an excellent carrier of information and energy,the advent and development of laser have been pioneering many new research fields.It provides a better tool and methods for people to study the interaction between light and the physical world,at the same time,varies of applications based on laser are derived,one of which is the optical manipulation technique.People found that small particles could experience a certain of force and had some interesting behaviors when were illustrated by a focused laser beam.This technique that utilizes the forces exerted by light beam to trap or manipulate small particles is iconically called optical tweezers,which is now widely applied in many science areas such as biology,physical chemistry and soft condensed matter physics.As the energy source of optical tweezers system,laser beam with proper modulations on magnitude,phase and polarization can significantly improve the performance of the system.In this thesis,we focus our attentions on the manipulation of nanoparticles by use of vortex Bessel beam,concretely these works were accomplished:firstly,we propose a method to generate a tightly focused field with controllable polarization through modulating the magnitude and polarization of the incident beam.Secondly,a method that generating evanescent vortex Bessel beam with any order by utilization of the angular selectivity of a photonics band gap structure is proposed,and the feasibility of manipulating metallic nanoparticles with the generated Bessel beam is researched.Thirdly,we propose an optical tweezers system to stably trap resonant metallic nanoparticles by use of a double-domain diffaction optics element(DOE)which induces the generation of negative scattering force.Lastly,we research the stable 3D manipulation of metallic nanoparticles under the absorption resonant wavelength based on a 4π focusing system whose symmetric structure eliminates the impact of the scattering forces.