  Novel triangular lattice photonic crystal fiber with a very large negative
flattened dispersion over the S+C+L band, and very high birefringence is
offered here. To investigate different optical properties of the proposed
fiber, finite element method (FEM) is deployed. The fiber presents a flattened
negative dispersion of $-698.5\pm 5 ps/(nm-km)$ over the wavelength of $1440
nm$ to $1600 nm$. Besides, the proposed photonic crystal fiber (PCF) exhibits a
high birefringence of $1.886\times10^{-2}$ at the wavelength of $1550 nm$.
Furthermore, the nonlinearity, single modeness, effective area etc. of the
proposed PCF are thoroughly discussed. The fiber would have important
applications in broadband residual dispersion compensation as well as
polarization maintaining applications.
