In this paper, a high sensitivity angle-sensing photodetector at the nanoscale is proposed, which mainly consists of SiO2 substrate and two columns of separate silicon nano-blocks and four gold electrodes. When the light in the incident plane perpendicular to the columns is obliquely incident on the silicon nano-blocks, they will absorb different light energy. Then the concentration of electron hole pairs in nano-blocks is also different, which will affect the photocurrent detected by the detector. Simulation results further show that the detection accuracy of the photodetector in the range of 0-45° can reach 0.152° when irradiated with TM polarized light. This angle sensing photodetector has many advantages, such as high sensitivity, low cost, easy integration. It can be used in the fields of information acquisition of light field, automatic driving scene perception and machine vision.
In order to accurately obtain the birefringence dispersion of liquid crystal variable retarder (LCVR) with wavelength ranges from 414nm to 702nm. Here, we propose an improved fitting method of birefringence dispersion by using the theory of polarized light interference. The birefringence of LCVR in 478nm is 0.3863 based on the improved method. The experimental result is 0.3862 and the percentage error is 0.026%, compared to the 1.761% of the original fitting method. This work provides an improved way to character the birefringence dispersion of LCVR.
In immersion lithographic illumination system, appropriate polarization illumination can improve the resolution and imaging quality. Thus it is of great significance to realize different polarization-modes. The zero-order half-wave plates are usually used to achieve conversion of different polarization-modes. However, large-diameter zero-order half-wave plate is too thin to manufacture and assembling. This paper presents a polarization-modes conversion method based on birefringent film. The properties of birefringence film is similar to zero-order half-wave plate, and the film is easy to manufacture. Theoretically, it can be estimated that the film thickness is 2.4μm correspond to 180° retardation in 193nm wavelength. The experiment indicates that the 180° birefringent film can convert linear polarization-modes successfully, which verifies the feasibility of the film as a substitute of zero-order half-wave plate in immersion lithographic illumination system. The method solves the problem that it is difficult to manufacture large-diameter zero-order half-wave plates, and provide a reference for the design of lithographic illumination system.
In this paper, we propose a dielectric cavity enhanced high reflective multiband waveplate based on nano-grating structure, which exhibits quarter waveplate at two wavelengths (λ=810nm and λ=1530nm) and half waveplate at another wavelength (λ=1100nm). The simulation results show that at the working wavelengths (i.e., 810nm, 1100nm and 1531nm) of the device, the reflections are larger than 94% and the average value is about 95% with polarization orientation at 45° . As compare with the traditional metal nanograting waveplate, it has large phase difference with the same geometrical parameters (period, aspect ratio and thickness), and it also does not need to rotate the polarization orientation of the incident light when it work at different wavelengths. It provides a great potential for applications in advanced nanophotonic devices and integrated photonic systems.
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