Research On Optical Tweezers Technology Based On Bottle Beam

Hollow beams have many novel and unique characteristics,such as barrel-shaped light intensity distribution,spiral wave fronts,singular center phase,spin angular and orbital angular momentum,small dark spot size,and no heating effect.These novel physical characteristics make hollow beams have broad application prospects in laser cooling and trapping,optical tweezers,and manipulation of microscopic particles(biological cells,atoms,molecules,and dielectric particles).Therefore,hollow beams have attracted many researchers’ Research interest.There is a more special type of beam in the hollow beam,which has attracted widespread attention.This hollow beam has a three-dimensional closed area with very small or even zero light intensity in the direction of propagation.This area is surrounded by a high-intensity light field distribution,like a special enclosed space.We call this type of laser beam a bottle beam.In recent years,bottle beams have been widely used in the fields of particle capture and optical micromanipulation due to the characteristics of three-dimensional closed dark hollow regions and extremely high intensity gradients.Therefore,how to easily obtain a bottle beam of appropriate size has become a research hotspot in recent years.In this paper,the design of the bottle beam and the capture of particles are studied and analyzed.The optical system is designed to produce the bottle beam more simply and efficiently.The optical tweezers force of the bottle beam to capture carbon nanoclusters particles is analyzed by using the software of COMSOL and MATLAB.The main research work of this paper can be divided into the following aspects:(1)A single beam tunable bottle beam was obtained using a semiconductor laser variable divergence angle shaping design and focusing with an axicon-lens system.The size and tunable characteristics of the bottle beam were studied and analyzed.(2)In order to widen the bottle beam and other measurement technologies,the generation method of the bottle beam is further improved,and the dual-beam design is used to form the bottle beam.The two beams of light are respectively generated through a designed double-axicon lens,and combined with the designed parabolic annular mirror lens,and combined to form a composite bottle beam of captured light.(3)Combining the simplicity of a single beam light trap system with the robustness of a dual-beam light trap system,a confocal beam design is used to generate a bottle beam;the confocal design provides better capture stability,less space occupation,and longer working range.(4)The influence of astigmatic elliptical Gaussian beams on bottle beams is analyzed.When the elliptical Gaussian beams with different eccentricities are incident light,the evolution process of the central diffraction spot and beam shape of the bottle beam formed by the axicon-lens system is studied.(5)Taking the dual-beam bottle beam as an example,the optical tweezer technology capture characteristics of the bottle beam are studied.Combined with the software of COMSOL and MATLAB,the trapping force and trapping characteristic analysis of carbon nanoclusters particles by a bottle beam were studied.