Fabrication And Characterization Of Polarization Grating Microarrays

Polarization imaging offers polarization information that is imperceptible by the human visual system.High resolution polarization imaging detectors can extract complete polarization properties from linearly polarized light and obtain more polarization information of targets.Polarizer is an important component in polarization imaging technology,which can shield and transmit incident light.With the development of micro/nano-fabrication technology,sub-wavelength metal grating has been proved to be an optical element with good polarization performance.Because of its small size and easy integration,this kind of polarization grating has a wide application prospect in polarization imaging and other fields.In this paper,electron beam exposure and focused ion beam etching were used to fabricate polarized grating microarrays,and the polarization characteristics were studied.Firstly,this report introduced the research background and significance,the current research worldwide,the development status,and the main research contents of the subject.The principle of polarization characteristic of polarization grating was analyzed by equivalent medium theory,and the structure of polarization grating was designed according to Stokes theory.Secondly,in the aspect of fabrication process,electron beam exposure and focused ion beam etching were introduced in this paper.The electron beam lithography system was introduced in detail.The working principle of the electron beam lithography,the parameter settings in the fabrication process including the interaction and influence of each parameter were studied in detail.The working principle,technological process and influencing factors of the plasma reactive etching technology were summarized.Polarized grating microarrays with different periods and different exposure doses in the same period were fabricated by electron beam lithography.At the same time,polarization grating microarrays were characterized by atomic force microscopy and scanning electron microscopy.The etching ratio between aluminium and photoresist during inductively coupled plasma etching process was calculated by morphology analysis after characterization.Meanwhile,this report also introduced the focused ion beam etching system,and the functional advantages,fabrication process and parameter settings of focused ion beam etching technology were studied in detail.Focused ion beam etching technology was used to fabricate polarized grating microarrays with different aspect ratios and double-layer polarized grating microarrays with different dislocation displacements in the horizontal direction of adjacent two-layer gratings.The process parameters affecting focused ion beam etching were analyzed.Finally,in the aspect of polarization performance detection,the performance detection system of polarization grating microarray was designed and established in this work.It was constructed to detect and analyze the performance of polarized grating microarrays with different periods,different exposure doses and different depth-width ratios.At the same time,the influence of different displacement in the horizontal direction of adjacent two-layer gratings on the performance of double-layer polarized grating microarrays was analyzed.The method of calculating extinction ratio and maximum polarization transmittance of polarization grating microarray performance parameters were presented.