Giant resonances near the split band edges of two-dimensional photonic crystals

We conduct a numerical study on the giant optical resonances near the split photonic band edges of two-dimensional square lattices. Their quality factors are 1 order of magnitude higher than those near the regular band edges. Such enhancement results from the efficient interference of multiple Bloch waves, which minimizes light leakage from the periodic pattern of finite size. The variation of the quality factor with the pattern size is nonmonotonic for the split band edge resonance, leading to an optimal size for the maximal quality factor.