Research On Femtosecond Vector Optical Field Micro-nano Processing Based On Spatial Light Modulation

At present,femtosecond laser micro/nano processing technology has been widely used in industrial production and scientific research due to its extremely short pulse,extremely high peak intensity,and small thermal effect in the area where the material is machined.However,due to the limitation of optical diffraction limit for the linearly polarized light field commonly used in femtosecond laser micro/nano processing,the precision and processing efficiency of femtosecond laser micro-nano processing are restricted in many applications.Therefore,in order to study the processing of femtosecond lasers with super resolution,high efficiency,and high reliability,in this paper,on the basis of the theory of femtosecond laser micromachining,the theoretical and experimental research on the micro nano machining technology of the femtosecond laser vector field is carried out by combining the vector field with the space optical modulation technology.Firstly,the characteristics,mechanism and application of femtosecond laser micro/nano fabrication were analyzed and discussed in detail.The methods of generating vector optical field and the principle of generating radial polarized vector optical field(RPVOF)by using radial polarization converter were summarized.Spatial light modulation was further discussed.The device implements the principle of light field regulation and combines it with a spatial light modulator to design a sine-shaped ternary hybrid filter(THF)that optimizes the properties of the vector optical field and produces a super-resolution optical needle array.Finally,the experimental platform of the femtosecond laser vector optical field micromachining system was bulit.On the basis,the ultra resolution longitudinal polarized light needle and the optical needle array are used to process the graphene oxide film and the quartz glass,and the performance of the femtosecond vector light field micromachining is analyzed,the main research work is as follows:(1)A femtosecond laser vector field optical field micro-nano processing technique with femtosecond laser combined vector field is proposed.The characteristics,mechanism and application of femtosecond laser processing are analyzed theoretically.The method of vector optical field generation and its application are summarized.The principle of generating polarized light beams in the longitudinal direction by means of radial polarization is compared.The tightly focused characteristics of the linearly polarized optical and the vector optical field are compared and analyzed.(2)Based on a radial polarization converter,an optical path that generates a radially polarized vector optical field is constructed.The principle of the spatial light modulator to realize light field regulation is studied and a sine-shaped ternary hybrid filter(THF)is designed in combination with a spatial light modulator.The particle swarm optimization algorithm optimizes the filter and produces a superresolution optical needle array.Based on this,an experimental light path system that generates a longitudinally polarized optical light field is built.The main components in the system are analyzed in depth,and vector optical fields are controlled on the drive software platform.(3)Under the premise of complete construction of the vector optical field experimental light path,an experimental platform for the femtosecond laser micro/nano processing system was designed and built,and the experimental light path of the femtosecond laser vector optical field micro/nano processing system was optimized,and the obtained experimental light path was used.The microhole machining experiments of graphene oxide thin films were carried out with super-resolution longitudinally polarized light guides and optical needle arrays.The spatial resolution,processing efficiency,and influencing factors of femtosecond laser vector optical field micro-nano processing were analyzed in detail.