Vacuum Cleaner,Cordless Vacuum,Handheld Vacuum,Stick Vacuum GUANGDONG DEERMA TECHNOLOGY CO., LTD. , https://www.deermaglobal.com
Shanghai Opto-Mechanics made progress in grating design based on simplified mode method
[ Instrument Network Instrument R & D ] Recently, the research team of the Information Optics and Optoelectronics Technology Laboratory of the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences has made new progress in grating design based on simplified mode methods. A simplified mode method was proposed for the design of multi-layer dielectric gratings, and a -2 order high-efficiency ultra-broadband high-tolerance diffraction grating was successfully designed. Related results were published online in the IEEE Photonics Technology Letters on March 15th.
Gratings have an irreplaceable role in spectral analysis, ultra-strong, ultra-fast lasers, high-end lithography, displacement measurement, astronomical measurement, etc., and are also one of the important indicators to measure the development level of a country's high-precision optical technology. The traditional grating design is optimized for the negative stage of the grating, but the resolution of the grating is proportional to the diffraction order of the grating. The higher the order, the higher the resolution. In order to improve the resolution of gratings, the production of high-order medium-staircase gratings is the most commonly used method. However, this method has a large number of orders and is difficult to manufacture. The efficiency value is usually only 65% ​​-75%, which severely restricts its wide application. .
In this study, the researchers used the simplified mode method to theoretically analyze the conditions of negative second-order high efficiency. The effective refractive index of each mode was obtained by solving the dispersion equation, and each propagation mode was analyzed to obtain a high efficiency of -2. The conditional expressions and initial parameters of the grating structure were further optimized by strictly coupled wave algorithm and simulated annealing optimization algorithm to obtain a -2 order ultra-wideband high-efficiency diffraction grating device. The diffraction efficiency of this structure can reach 99.58% at the highest, and achieve high-efficiency output of more than 95% in the range of wavelength from 1.454μm to 1.531μm and the angle of incidence of 37.32 ° -43.3 °. The research results show that the structure also has excellent tolerance characteristics and strong feasibility, which is suitable for industrial mass production. This is the first time a multilayer broadband-2 order high-efficiency diffraction grating structure analyzed and designed by simplified mode theory method, which provides the possibility for the simplified mode theory method to be applied to the design of multilayer structure gratings.
Relevant work was supported by the Shanghai Science and Technology Commission and the Chinese Academy of Sciences Key Frontier Science Key Project.