“…Through photonic band gap (PBG) and slow light effect [2], various optical devices based on photonic crystals have been demonstrated with ultra-small footprints, such as waveguides [3], resonators [4], filters [5] and bends [6]. Among them, high efficient photonic crystal waveguide (PCW) bend can be achieved with the spatial extent on the order of the wavelength, which is a promising candidate for compact PICs [7][8][9].…”