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Large anomalous dispersion at short wavelength and modal properties of a photonic crystal fiber with large air holes

We investigated the dispersion and modal properties of a photonic crystal fiber (PCF) with larger air holes (LAH). The theoretical and numerical results show that large anomalous group-velocity dispersion at short wavelength down to around 700 ~ 800 nm can be achieved in a LAH-PCF with small pitch. Furthermore, the high-order modes usually are excited in a LAH-PCF when the optical field is launched from a traditional single-mode fiber, and all the excited modes will interfere when they propagate along the PCF. Finally, the properties of the excited modal spectrum and the multimode interference are determined by the normalized pitch and the normalized hole size of the PCF. All of these will provide references for the smoothing applications of the LAH-PCF