Manipulation And Applications Of Optical Tweezers For Nanowires

As the technology of optical tweezers develops,the manipulation of optical tweezers can be applied to nanotechnology,which is one of the most active frontier fields today.Optical tweezers can capture and manipulate small objects with high precision,providing a new effective means for the assembly and fabrication of nano devices.In this thesis,beam shaping is used to design and generate novel beams to achieve specific manipulation and application of nanowires.The main research contents and conclusions are as follows:(1)An auto-alignment beam is designed to realize auto-alignment of nanowires.The auto-alignment beam comprises two semicircles.The intensity gradient force is used to capture the nanowire transversely,and the phase gradient force drives the nanowire to rotate.The intensity gradient force and phase gradient force are balanced to realize the alignment of the nanowire.The design proves the feasibility of the beam for the alignment control of the nanowire from the perspective of mechanics.The intensity and phase of the auto-alignment beam are simulated by using the complex amplitude shaping technique,and an autoalignment beam is generated for experimental manipulation.(2)Realization of auto-alignment control of nanowire array.The holographic optical tweezers platform has been built to realize the autoalignment control of nanowires.The experimental results show that the auto-alignment beam can quickly achieve the high-precision alignment of nanowire,and the nanowire array arrangement is realized.The technology is simple to operate and has high alignment accuracy,which provides a new and effective control method for large-scale arrangement of nanowires.(3)Optical tweezers are applied to accurately cutting nanowires,and the fracture mechanism of nanowires is developed.On the basis of a simply supported beam model,the ultimate load of nanowires is calculated by strength theory and deformation theory,and the force exerted by optical tweezers is proved to be the cause of the fracture of high aspect ratio nanowires.The experimental result has verified the mechanism.The precision cutting of nanowires with optical tweezers has potential applications for micro-machining and manufacturing of nanowire-based micro/nano devices.