  We demonstrate a fiber-based source of polarization-entangled photon pairs at
visible wavelengths suitable for integration with local quantum processing
schemes. The photons are created through birefringent phase-matching in
spontaneous four-wave mixing inside a Sagnac interferometer. We address
entanglement degradation due to temporal distinguishability of the photons to
enable the generation of a spectrally unfiltered polarization-entangled
photon-pair state with $95.86\pm0.10%$ fidelity to a maximally entangled Bell
state, evaluated with a tomographic state reconstruction without applying any
corrections or background subtractions. Owing to the large birefringence of the
fiber, photons are created far detuned from the pump, where Raman contamination
is negligible. This source's spatial mode and ability to produce spectrally
uncorrelated photons make it suitable for implementing quantum information
protocols over free-space and fiber-based networks.
