Dispersion Engineering in Single-Polarization Single-Mode Photonic Crystal Fibers for a Nearly Zero Flattened Profile

We propose a systematic solution to the problem on dispersion engineering in single-polarization single-mode (SPSM) photonic crystal fibers (PCFs) for a nearly zero flattened profile. Based on dispersion-approximating and -normalizing methods as well as a clever engineering strategy, we have succeeded in a design of SPSM PCF with nearly zero flattened dispersion {\text{0.82}}\pm {\text{0.30}}\,\text{ps}/\text{nm}/\text{km} over a broad band of {\text{1.12}}\sim {\text{1.51}}\,\mu{\text{m}}. Moreover, such a fiber presents a very low confinement-loss level, which is less than 0.001 dB/km over the operation band.