Band gaps structure and semi-Dirac point of two-dimensional function photonic crystals
Zhang Si-Qi1, Lu Jing-Bin1, Liang Yu2, Ma Ji2, Li Hong3, Li Xue1, Liu Xiao-Jing2, Wu Xiang-Yao2, †, Meng Xiang-Dong2
       

(a) The triangular lattice structure of two-dimensional photonic crystals, (b) the first Brillouin zone of the triangle grid.