Study On Optical Manipulation Methods And Characteristics With Microstructured Optical Fiber

Optical tweezers(OT)are widely used in biology,chemistry,colloid science and physics because of non-contact,non-mechanical and versatile.With the deepening of research,the optical manipulation method based on optical tweezer has expanded from traditional optical trapping to optical cooling,stretching,binding,rotating,transporting,sensing and measuring.Various particle manipulation methods have been applied in particle screening,microstructure preparation,targeted drug delivery and research on the mechanical properties of biological cells and molecules.Based on special optical fiber and multiple fiber endface processing methods,this thesis successfully achieved optical trapping and particle sizing of high-index particles,optical trapping of low-index particles,optical trapping and curvilinear guiding of high-absorbing particles,respectively.This thesis not only extended the way of optical manipulating particles,but also revealed the distinct mechanism between different types of particles and light.It explained the principle of OT based on optical radiation pressure and photophoresis force,which provided a reference for the practical application of OT technology.The principle of OT was divided into two parts,optical radiation pressure and photophoresis.And the theoretical models and calculation methods of optical forces were explained in this thesis.It provided theoretical support for the following simulation and experimental research.The optical trapping and particle sizing of high-index polystyrene spheres were realized with coaxial-core optical fiber tweezer.Based on two-beam interference,this method obtained the particle size information from particle and fiber endface.The main factors affecting the particle size measurement range and measuring errors were also discussed.The particle size measurement range was 10 ?m-26 ?m.This method was real-time,dynamic and non-contact.The optical trapping of low-index yeast cells with annular-core fiber tweezer were achieved.Annular beam outputting from the fiber was focused by the silica microsphere,the yeast cell was trapped in the annular dark field behind the focus point.The order of magnitude of optical trapping force was tens of PN.Because of dark field trapping,this method avoided most of the thermal damage.In addition,this kind of microlen-typed fiber had simple manufacturing process,good light convergence effect,high coupling efficiency and great application prospect.The optical trapping and X-typed curvilinear transporting of high-absorbing particles with twin-core fiber tweezer were achieved.The motion of the absorbing particles in pure liquid glycerol was dominated by the ??-type photophoretic forces.This method performed the stably manipulation and X-typed curved reciprocating transporting of the high-absorbing particles by changing and controlling the incident laser powers.The effective transport distance of particles was up to 60 ?m.This novel particle transporting method expanded the application of strongly absorbing particles in particle screening,targeted drug delivery and particle clearing.