Simple and universal method in designs of high-efficiency diffractive optical elements for spectrum separation and beam concentration
Xu Wen-Qi1, Lin Dong-Feng2, Xu Xin2, Ye Jia-Sheng1, †, Wang Xin-Ke1, Feng Sheng-Fei1, Sun Wen-Feng1, Han Peng1, Zhang Yan1, Meng Qing-Bo2, Yang Guo-Zhen2
       

(color online) Optical focusing efficiency of the designed SSBC DOEs with respect to the maximum permitted phase. The maximum permitted phase is involved with the central wavelength. The green, red, cyan, magenta, and blue curves correspond to the 8-level, 16-level, 32-level, 64-level, and continuous DOEs, respectively.