  In this Letter, a linear scheme to generate polarization entanglement at 1.5
um based on commercial polarization maintained dispersion shifted fiber
(PM-DSF) is proposed. The birefringent walk-off effect of the pulsed pump light
in the PM-DSF provides an effective way to suppress the vector scattering
processes of spontaneous four wave mixing. A 90 degree offset of fiber
polarization axes is introduced at the midpoint of the fiber to realize the
quantum superposition of the two correlated photon states generated by the two
scalar processes on different fiber polarization axes, leading to polarization
entanglement generation. Experiments of the indistinguishable property on
single side and two-photon interference in two non-orthogonal polarization
bases are demonstrated. A two photon interference fringe visibility of 89\pm3%
is achieved without subtracting the background counts, demonstrating its great
potential in developing highly efficient and stable fiber based
polarization-entangled quantum light source at optical communication band.
