Light Field Manipulation Properties of Vanadium Dioxide Microstructure
Objective In recent years,with the development of nanotechnology,research on vanadium dioxide(VO2)microstructures focuses on preparation,property control,and application,particularly in areas such as smart windows,storage devices,and optoelectronic devices.The light field control performance of VO2 microstructures has shown great potential in fields like photocatalysis,optical sensing,and optoelectronic devices.Currently,the mainstream preparation methods include solution methods and thermal decomposition methods,but they have drawbacks such as complex processes.We employ a self-assembly method to prepare tungsten-doped VO2 microstructures and thoroughly explore their light field control performance to achieve practical applications.Methods A homemade circular polystyrene(PS)mold with a diameter of 10.0 mm and a thickness of 2.0 mm is placed on a clean and level desk.Adhesive tape is applied on the desktop beneath and above the mold,and the polyethylene(PE)lines are cut into long and short threads,which are then interlaced densely on the mold and fixed at both ends with tape.After securing the mold,it is flipped,and two drops of nanosolution with a W-doped atomic ratio of 2%are dripped from 1 to 2 cm above the mold,waiting for it to solidify.Once solidified,the long thread is carefully separated from the microstructure,leading to WxV1-xO2/glass microstructures under different numbers of PE lines.Finally,the sample made with nanosolution with a W-doped atomic ratio of 2%and 9 PE lines exhibits sound symmetry,clarity,integrity,and uniformity.The above experiment is repeated by utilizing WxV1-xO2 nanosolution with a W-doped atomic ratio of 2%and 9 PE lines,with the formation process of the WxV1-xO2/glass microstructure recorded.The solution first spreads outward to the edges of the homemade experimental mold,with the relatively thin center of the solution and relatively thick edges.The PE lines form symmetrical crescent-shaped films,which gradually thicken inward.Subsequently,the surface morphology of the film samples is tested by adopting the German ZEISS GeminiSEM 300 scanning electron microscope.Then,a testing platform is set up by employing a 980 nm wavelength laser,with the optical path shown in Fig.4.Thermal-sensitive paper is adopted to help align the optical path,ensuring that the laser passes through the film.Meanwhile,a helium-neon(He-Ne)laser is utilized to replace near-infrared light to assist in observing diffraction patterns.Results and Discusses On the set-up near-infrared light transmittance measurement device,by replacing the light detector with a screen and the infrared light with a He-Ne laser,distinct moiré patterns can be observed for the nine vertically aligned WxV1-xO2/glass microstructures.After appropriately adjusting the relative position of the light-emitting device and the VO2 microstructure,the moiré patterns can be observed.By keeping the horizontal distance between the light source and the microstructure unchanged,and adjusting the vertical relative position of the light source and the WxV1-xO2/glass microstructure,it is possible to observe whether moiré patterns form.Additionally,the vertical adjustment between the light source and the WxV1-xO2/glass microstructure is achieved by utilizing the LD-60-CM(XYZ-axis)high-precision manual displacement stage.For the cross and asterisk VO2 microstructures,the diffraction fringes can be observed to change as the relative vertical position between the light source and the WxV1-xO2/glass microstructure is altered.Meanwhile,the diffraction patterns show two types of stripes intersecting to form a cross at times and alternating patterns at other times.Based on the diffraction patterns of the cross and asterisk WxV1-xO2/glass film microstructures under red laser light,we can observe that compared to the patterns of the 9 WxV1-xO2/glass thin film microstructures under visible light,both the cross and asterisk WxV1-xO2/glass microstructures show intersecting grid patterns,which are moiré patterns produced by the grating superposition.Computer simulation of moiré patterns is realized by adopting Python code.The transmittance data of different WxV1-xO2/glass thin films and microstructures at different temperatures are obtained via a variable-temperature infrared testing platform.Conclusions We innovatively fabricate the WxV1-xO2/glass thin film microstructure by employing a simple and feasible method of mold preparation.By observing and testing the optical properties of the WxV1-xO2/glass microstructure,we conclude that the sample with a W-doped atomic ratio of 2%has better formation and light field control performance.Furthermore,cross and asterisk microstructures are designed,and a He-Ne laser is adopted as the light source to obtain diffraction patterns.After light passes through the WxV1-xO2/glass microstructure,diffraction phenomena occur,and it is observed that within a certain range,adjusting the relative position of the light source to the vertical direction of the microstructure allows the observation of changes in the diffraction pattern of the microstructure.A self-built variable-temperature infrared testing platform is adopted to achieve control of the diffraction pattern direction,and the computer simulation of the moiré patterns generated by the grating superposition is consistent with the experimental results.This demonstrates that the optical properties of the W-doped VO2 microstructure prepared by a simple,low-cost,and easy-to-implement method can be quantitatively controlled.We will focus on developing devices that can finely control the light field control performance of the WxV1-xO2/glass microstructure in subsequent studies to achieve industrial applications.
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