Searching the flat band throughout the entire Brillouin zone in photonic crystals based on V-shaped dielectric pillars

In this work, we theoretically simulated the photonic band structures of the proposed photonic crystal based on two-dimensional V-shaped dielectric pillars with the same V-direction and opposite V-direction. The flat-band behavior throughout the entire Brillouin zone was investigated by analyzing the bandwidth variations with optimized parameters and other performances such as electric field distribution and group index. The bandwidth can reach the minimum value of <i>Δ</i><i>ω</i><i>a</i>/2<i>π</i><i>c</i>=0.00888 and 0.00579 for two cases. The results provide support for searching the flat band throughout the entire Brillouin zone in photonic crystals.